Q6 - The calm, shallow waters of coastal estuaries are easil

by **tommywallach** Mon Aug 06, 2012 3:10 pm

PT 65, S4, Q6 (Inference)

(E) is correct.

This is an inference question. Remember, on these questions you should not go looking for the argument’s core. Instead, try to keep track of all the various facts, so that you don’t leap to an extreme conclusion. The answer to an inference question is often quite boring, even a restatement of something written in the stimulus itself.

In this case, we’re given a series of causal relationships which we need to keep close track of: nutrient-rich sewage pollutes estuaries -> algae proliferates -> algae feeds microorganisms toxic to fish -> most fish are killed. Now we need to look for an answer that fits in with this causal chain.

(A) This passage only talks about estuaries that are polluted by sewage. For all we know, an estuary could occasionally be polluted with cyanide, which kills all the fish.

(B) This passage only talks about one type of microorganism, the kind that is toxic to fish. We can’t infer the speed at which other types of microorganisms might reproduce.

(C) This might seem plausible, but always be nervous of extreme language when solving inference questions ("in any way other..."). Though we know that sewage does hurt fish through the toxic microorganisms, that doesn’t mean it doesn’t hurt fish in other ways as well. Maybe it also clogs their gills.

(D) While we know that algae does proliferate in estuaries polluted with sewage, we are never told that’s the only way for algae to proliferate in estuaries. Pesticides could cause the same outcome, or various climatic phenomena

(E) This is a direct restatement of our chain of causality.

It’s important to notice definitive versus non-definitive language when solving inference questions. (B), (C), and (D) all use definitive language ("are more likely to die..." "reproduce more quickly" "do not harm fish in any way...") whereas (A) and (E) both use non-definitive language: "generally more likely to die..." "can result...". On an inference question, non-definitive language is far more likely to be correct than definitive language.