Q9 - It is not known whether

[tzyc]

How do we know (A) completes the the argument from the stimulus...?
I chose (E) and think somehow it includes what (A) says...
Thank you

[tommywallach]

Let's take this question top to bottom. This is technically an inference question, though that can be hard to see. However, we are inferring where the argument would go based on what's come before, which is no different from any question asking "Which of the following can be inferred from the information above?"

Knowing that, we just need to think about the premises that are given:

1) It's unknown if BSE can be transmitted at all stages of infection.

2) If it can, there is a reservoir of infected cattle incubating BSE.

3) There are no diagnostic tests to identify infected animals before the animals show overt symptoms.

4) Direct transmission has occurred.

(A) Correct. Let's think about what would happen if we did this. Any cow/bull with symptoms will be killed. However, it will already have infected other cows, which don't yet show symptoms. So we'll never be able to get rid of the disease this way.

(B) is totally plausible. If we can develop a drug that kills BSE, then we can use it to treat all the cows at once, so BSE can't be spread.

(C) may be totally dramatic, but it would work. If we kill every single infected cow, then start over in an area without any BSE, we will get rid of BSE.

(D) is also a great idea. If we inoculate all cows against any future BSE, then let all the infected ones die, we'll be left only with healthy cows that can't develop BSE.

(E) is a big hypothetical, but if it could be accomplished, it would work. Right now, we know there isn't a diagnostic test that works to reveal cows before they show symptoms. But if we could see every single cow that had the illness, we could kill them all, and all the cows that were left would be clean.

Remember, you aren't trying to work out why the right one is right so much as you are trying to work out why all the wrong answers are wrong.

Let me know if that makes sense!

-t

[mvh34891]

How is (C) possible? Wouldn't our inability to detect BSE fully prevent us from "raising cattle only in areas to which BSE is not known to have spread"? Isn't that the whole point, that there is no diagnostic test for presence of the disease in early stages, and therefore no way of definitively knowing that it has not spread to an area?

[maryadkins]

It says "known not to have spread," not "not known to have spread," and the difference is important.

We may not know which individual animals are infected of a clan (herd? school? ) of cattle, as we are told in the stimulus, but if we KNOW it's not in an area at all, we can be sure the individuals are safe.