A popular beach has long had a dolphin feeding program in which fish are given to dolphins several times a day; many dolphins get as much as half of their food each day there. Although dolphins that first benefit from the program as adults are healthy and long-lived, their offspring have a lower life expectancy than offspring of dolphins that feed exclusively in the wild.
Which of the following, if true, most helps to explain the lower life expectancy of offspring of dolphins feeding at the beach compared to other young dolphins?

A. Sharks that prey on dolphins are less common in the open seas off the beach than in many other areas of the open seas where dolphins congregate.

B. Many of the adult dolphins that feed at the beach are females that nurse their offspring there.

C. The fish given to the dolphins at the beach are the same types of fish that dolphins typically catch in the wild.

D. Many dolphins that feed at the beach with their offspring come to the beach only a few times a month.

E. Adult dolphins that feed at the beach spend much less time teaching their offspring how to catch fish in the wild than do other adult dolphins.

Why not A is correct?

My answer is E.

A is saying that the sharks are less common at the beach areas ..so it is not solving the puzzle on why the offspring at beach have lower life expectancy. (despite the fact that there are fewer sharks)

E says that , or helps to build the gap, the offspring born at beaches are not good at swimming ( since their parents didn't spend enough time teaching them how to swim) so this can be a reason that they have lower life expectancy.

A is exactly the opposite of what we want. It would help if there were MORE sharks near the feeding area, not fewer..

_________________
Tim Sanders
Manhattan GMAT Instructor

If E is the answer, A is also a contender because, adult dolphins that feed at the beach don't teach their children how to escape from sharks.

As E is present in the answer choices, we need to select E which is better than A: if adult dolphins teach their children how to catch fish in the sea, obviously this teaching includes how to escape from sharks as well, which is what explained by A.

I think that all the answer choices except E are not relevant to the explanation.

A. Sharks that prey on dolphins are less common in the open seas off the beach than in many other areas of the open seas where dolphins congregate.

It means that sharks reside more often in an open sea. Thus, dolphins who take food near the beach are in much safe.

B. Many of the adult dolphins that feed at the beach are females that nurse their offspring there.

This is not relevant to the problem.

C. The fish given to the dolphins at the beach are the same types of fish that dolphins typically catch in the wild.
that nurse their offspring there.
This is not relevant to the problem.

D. Many dolphins that feed at the beach with their offspring come to the beach only a few times a month.
This is not relevant to the problem. This sentence doesn't explain why those dolphins who take fish near the beach are in danger.

E. Adult dolphins that feed at the beach spend much less time teaching their offspring how to catch fish in the wild than do other adult dolphins.
This is correct. Because of lack of time for teaching off-springs don't know how to catch fish themselves.

chembeti, your analysis of A is quite a stretch and requires not only additional inferences about the behavior of dolphins but also several leaps of logic. you should seek to avoid this on GMAT questions. a correct analysis of this problem (according to the way the GMAT analyzes questions) reveals that A is the exact opposite of what we want..

_________________
Tim Sanders
Manhattan GMAT Instructor