The female earless seal has a gestation period that usually spans nine

OFFICIAL EXPLANATION

Overview:

In this question, the student is given information about the female earless seal and the events surrounding gestation and breeding. According to the passage, the female earless seal gestates for anywhere from nine to eleven months (depending on the variety of earless seal) and gives birth to and nurses only one pup at a time. The passage notes that during a bad season up to three female earless seals in a colony will die three months after giving birth, although all of the pups usually survive. Considering that other female seals cannot nurse orphaned pups – since each lactating female can nurse only a single pup – a natural expectation is that the pups would die with their mothers, since they have no one to nurse them. However, the pups all survive. The question asks the student to select an answer choice that best explains this discrepancy.

The Correct Answer:

D Answer choice (D) indicates that the mother seals nurse the pups only up to a month at the longest, suggesting that after a month the pups are capable of locating food for themselves. This answer choice thus provides a sufficient explanation for why the mother seals might die three months after giving birth, while the pups survive: the pups are finished nursing by this point and can find their own food. Answer choice (D) is correct.

The Incorrect Answers:

A Answer choice (A) contradicts the statement in the passage that the mother seals give birth to and nurse only one pup at a time and then use most of their energy to nurse that single pup, often fasting while she is lactating. Answer choice (A) cannot be correct.

B Answer choice (B), although interesting, is irrelevant to explaining the discrepancy. The question asks for a reason that the pups survive although the mothers do not; answer choice (B) simply diverts from this point to say that very often the mothers do not die. Moreover, answer choice (B) ignores the statement in the question about the reason for mothers dying during a bad season. Answer choice (B) is clearly incorrect and can be eliminated immediately.

C Answer choice (C) does not explain why seal pups survive even when their mothers die. It is not surprising that some female seals do not give birth (for instance, because they are not sexually mature). The existence of such seals alone does not explain why more pups survive (there is nothing in the passage to suggest they would nurse the orphaned pups, for example).

E As with answer choice (B), answer choice (E) ignores the central question by offering interesting but irrelevant information. The question asks for a reason for the discrepancy between mother seals dying three months after giving birth while the pups survive. Answer choice (E) merely provides information about some of the mothers living up to six months. Because this is unrelated to why pups live when mothers die, answer choice (E) is incorrect.