Oceanologist: Recently an unprecedented number of dead dolphins washed

OFFICIAL EXPLANATION

We are looking for an additional factor that could account for the dolphins washing upon the shore. (B) gives us such a factor, i.e., toxins released by a major oil spill.

(A) does not provide an additional factor that could account for the beached dolphins. It only discusses location.

(C) almost points at an additional factor, since PCB could help account for what happened to the dolphins. At the same time, (C) does not provide an additional factor beyond what's in the text. It does not offer an explanation as strong as the one provided by (B). The point is that the oceanologist needs something other than brevotoxins to explain the dolphins' deaths. C gives us information about PCB, but doesn't tell us anything else about how much PCB there was or whether it caused the deaths. In fact, it actually gives us information that PCB is not so bad: "the dose of PCB a dolphin encounters in the wild is unlikely to pose a lethal threat to a dolphin."

(D) does not shed any insight into a possible cause.

(E) does the opposite. It suggests that brevotoxins and PCB were responsible for the dolphins washing upon shore. Thus, it doesn't necessarily add weight to the biologists' doubts. Yes, it does say that PCB causes "visible lesions," but we don't know if lesions actually cause death in dolphins. We would have to infer this, and anytime you make this type of inference to choose an answer with these question types, you usually end up in trouble. Also, the first part of the answer choice is a bit ambiguous and doesn't necessarily show that PCB and b-toxins are killers; it only states that they "exercise different effects on an organism." For all we know, some of these effects might be good or might be bad.

FAQs: What is this question actually asking?

Let's take another look at the question wording:

Which of the following, if true, does most to help explain the oceanologist’s doubt that the brevotoxins were the primary cause of the dolphins washing upon shore?
We can rephrase this to say:

Which of the following, if true, does most to help explain why the oceanologist does not think that the brevotoxins were the primary cause of the dolphins washing upon shore?

Well, if the oceanologist does not think that the brevotoxins were the primary cause of the dolphins washing upon shore, then the oceanologist must think that there is another cause that was the primary cause. Therefore, we need to find what the primary cause could be.

I don't understand why (B) is the correct answer. The question is asking for me to provide support for the fact that brevotoxins couldn't be the sole cause of the dolphins' death. However, (B) does not do this.

First, remember to choose an answer choice that supports the biologist's conclusion that the dolphins died NOT just from brevotoxin; some people out there do think that it was this toxin, but the oceanologist thinks it must have been something else.

It's understandable to be hesitant to choose (B), since it seems like something that was already said in the passage. But actually, (B) does add more detail, and thus support, to the biologists' doubt. Choice (B) not only gives us a source of both the b-toxin and the PCB, but we are also told that other "deleterious industrious pollutants" were released. PCB is just one of them. So this answer choice doesn't really repeat what's been said.