Q6 - A study was designed to

[inesa909]

I struggled a lot between choosing B or C. I mistakenly chose C because it proved that there were adverse effects of rigging on sea-bottom animals. I also see how B would taint both samples.

[a3friedm]

So we know from the stimulus that they are trying to study the effects offshore oil rigs have on animal life at the bottom of the sea. "The study compared the sea-bottom communities near rigs with those located in control sites several miles from any rig and found no significant differences. The researchers concluded that oil rigs had no adverse effect on sea-bottom animals."

Before getting into the answer choices our question stem appears to have a pretty big gap in logic, the two communities, close to shore, both contained no significant differences; thus oil rigs had no adverse effect on sea-bottom animals. So what could be wrong with this? well for starters, the oil could be carried out to sea and then settle to the ocean floor, ie capitalizing on the flaw that the conclusion is much broader than can be gathered from the study. Answer choice (B) gives us that almost word for word

I can see how (C) could be tempting, but it doesn't really do what we need it to. If contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea bottom animals but instead reduces species diversity as well as density of animal life does that hurt the argument? It could make the effects of oil rigs harder to study, but it doesn't take advantage of that really big gap between no significant differences between the communities, and the no adverse effect on the sea-bottom as a whole. Even if it did make the differences less apparent, I don't think that really weaken are argument here.

Hope this helped

[maryadkins]

Great discussion! And I agree about (C). We don't know how this influences the link between the rigs and the animal life as established in the study.

(A) is out of scope.
(D) is irrelevant.
(E) creates and issue that doesn't exist and we don't know how that affects the argument.

Hope this is clearer for you now. Thanks for the post a3friedm!

[sumukh09]

I was between B) and C) on this question as well and ended up opting for C).

What particularly attracted me to C) was "reduces density of animal life." I thought for sure this was an adverse affect on sea bottom animals. I wasn't quite sure what was meant by "density of animal life" but it doesn't sound beneficial for sea bottom animals. Anyone care to explain what that means? Thanks in advance.

[dl0120]

I was between B) and C) on this question as well and ended up opting for C).

What particularly attracted me to C) was "reduces density of animal life." I thought for sure this was an adverse affect on sea bottom animals. I wasn't quite sure what was meant by "density of animal life" but it doesn't sound beneficial for sea bottom animals. Anyone care to explain what that means? Thanks in advance.

"reduce density of animal life" means to kill animals so that there are less of them spread out over the same volume.

To compare it to humans, let's say there's a city of 10 square miles with 1000 people. A disease kills 900 people, so there's 100 people left for the same 10 square mile. The densities are 1000/10 = 100 ppl per square mile initially and 100/10 = 10 ppl per square mile after disease.

To reduce density rather than destroy all sea bottom animals simply means it kills some animals, but not all.

Destroying all sea bottom animals would be similar to if the disease killed all 1000 people in that city. Then the density would be 0/10 square mile = 0.

[agersh144]

I was stuck between B and C like the above posters but I had issue with the vagueness of the term "considerable distances." Is considerable distances several miles? Is it more than several miles? It seems like in questions like these when your forced to make an implication that isn't clear it typically tends not to be the correct answer choice. Although in this one I can see that if we assume that considerable distances is more than several miles than B is a good answer but during test conditions I erred toward the side of clear untoward effects of reduction of both species diversity and density as ostensible indicators of the potential adverse consequences of oil rigs.

Can someone walk me through their logical process when breaking this down during test time and under pressure. Much appreciated..

[fmuirhea]

agersh, I agree that "several miles" and "considerable distance" are somewhat nebulous terms, but they're comparable enough for this question. I might chalk it up to this being a fairly old LSAT, where the language wasn't quite as precise.

As for the logical thought process, I think it's useful to focus on the method of argumentation at play to uncover the assumptions and thus find the potential point of weakness to exploit.

The evidence makes reference to a comparative study. Two areas were studied: one near oil rigs (the implication being that this site would be affected by the oil) and one out of the immediate vicinity of any oil rigs (the implication being that this site would not be affected by the oil). You'll notice that neither of these parenthetical implications is outright stated - they are the assumptions being made. The first one is reasonable enough (close to oil = affected by oil), but the second is less certain (several miles from oil = not affected by oil).

The argument leans on the observed similarity between the two sites as proof that oil has no adverse effects on sea animals, but this can only be true if we confirm the truth of the assumption that the distant site is not affected by the oil. If it were so affected, then we'd be back to square one, because the observed similarity could simply be the result of the oil affecting both sites in the same way. (B) brings up this consideration, and effectively attacks one of the assumptions underpinning the argument.

When arguments rely on comparisons (or, really in this case, contrasts) to make a point, look for answer choices that discuss the validity of the comparison/contrast at play. The broad assumption is that the comparison/contrast is valid, that there is not some important distinction (or, in this case, similarity) that compromises the strength of the evidence.

[agersh144]

Great explanation, thanks for walking me through your reasoning, much appreciated!

[roflcoptersoisoi]

Argument: There is no significant difference between sea communities near oil rigs and those in control sites situated near any oil rigs. Therefore, oil rigs have no adverse impacts on sea communities.

Answer choices:
(A) Commercially important fish depend on sea-bottom animals for much of their food, so a drop in catches of those fish would be evidence of damage to sea-bottom communities
(B) The discharge of oil from offshore oil rigs typically occurs at the surface of the water, and currents often carry the oil considerable distances before it settles on the ocean floor.
(C) Contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea-bottom animals but instead reduces species diversity as well as density of animal life.
(D) Only part of any oil discharged into the ocean reaches the ocean floor: some oil evaporates and some remains in the water suspended drops.
(E) Where the ocean floor consists of soft sediment, contaminating oil persists much longer than where the ocean floor is rocky.

I easily eliminated answer choices (A), (D) and (E) but fell for the trap answer choice (C), the correct answer was (B).

The principle reason for which I think I selected C was the fact that I did not do an adequate job at identifying the presupposition made by the author thus severely constraining my ability to anticipate the answer choice.

A flaw/assumption I identified as being made by the author was that he/she: "Presumed that the adverse effects precipitated by oil rigs would be projected externally and therefore would be discernable to observers", I thought to myself whilst criticizing this assumption that perhaps the oil from the rigs affected sea animals only internally (e.g., damaged their internal organs) something like that. However, the gap wasn't at all addressed in the answer choices so I guess I completely missed the ball on anticipating the answer.

Another reason for which (C) was attractive to me was the fact that it mentioned industrial effluent which I conflated with oil from the rigs. I'm habitually very abstract when reading LSAT questions to avoid making unwarranted assumptions and operating on conjecture, however in my estimation this was a perfectly reasonable assumption to make, however, feel free to correct me if you think otherwise. Indeed, while answer choice (C) conceded that the sewage and industrial effluent didn't eliminate all sea animals, it clearly stated that it reduced density and diversity by presumably killing them off which in my view clearly weakens the premise-conclusion relationship. Obviously, I'm wrong, however after mulling over this question for nearly 45 minutes, I still cannot articulate a good reason for why it is incorrect and B is correct.

[LauraS737]

The reason why answer choice (C) is wrong is because it is vague and unclear: (C) states that contamination from sewage and industrial effluent reduces species diversity etc., but we don't know what is causing the contamination of sewage and industrial effluent. It can be the oil rig, but that's not the only thing that can cause contamination. What if it's not the oil rig and it's some other crazy human invention that's causing the contamination. Because this answer choice leaves that gap open, it is a worse answer choice than (B) which directly addresses the oil rigs.

[WhimsicalWillow]

Read the answer choices carefully and you will see why B is correct.

Answer choices:
(A) Commercially important fish depend on sea-bottom animals for much of their food, so a drop in catches of those fish would be evidence of damage to sea-bottom communities

No, we are focused on weakening the argument that oil from oil rigs does not hurt the sea bottom creatures.

"evidence of damage" what kind of damage? it's not specific.

(B) The discharge of oil from offshore oil rigs typically occurs at the surface of the water, and currents often carry the oil considerable distances before it settles on the ocean floor.

Specifically uses the word "oil from offshore oil rigs" to show where the oil came from

(C) Contamination of the ocean floor from sewage and industrial effluent does not result in the destruction of all sea-bottom animals but instead reduces species diversity as well as density of animal life.

No, "sewage and industrial effluent (wastewater treatment) is not in the study. The focus is on oil rigs and sea bottom animals and weakening the argument that the oil from oil rigs has no effect.

(D) Only part of any oil discharged into the ocean reaches the ocean floor: some oil evaporates and some remains in the water suspended drops.

Only uses the word “oil”. (What kind of oil? Olive oil? It’s not specific)

(E) Where the ocean floor consists of soft sediment, contaminating oil persists much longer than where the ocean floor is rocky.

“contaminating oil” (Study has not proven whether the oil is contaminating. What makes it contaminating oil? A contaminating oil can be something other than oil from oil rigs)

I picked B via process of elimination POE based on the language because I was stuck between B and E given that if different parts of the ocean floor have different sediment that contain the oil from oil rigs (rocky vs. soft), it would directly impact the conclusion. However, “contaminating oil” makes E wrong.