求解一道狒狒逻辑

36. Sometimes when their trainer gives the hand signal for “Do something creative together” two dolphins circle a pool in tandem and then leap through the air simultaneously. On the other occasions, the same signal elicits synchronized backward swims or tail-waving. These behaviors are not simply learned responses to a given stimulus. Rather, dolphins are capable of higher cognitive functions that may include the use of language and forethought.

Which one of the following, if true, most strengthens the argument?

(A) Mammals have some resemblance to one another with respect to bodily function and brain structure.

(B) The dolphins often exhibit complex new responses to the hand signal.

(C) The dolphins are given food incentives as part of their training.

(D) Dolphins do not interact with humans the way they interact with one another.

(E) Some of the behaviors mentioned are exhibited by dolphins in their natural habitat

E为啥不对？在自然栖息地就是野外，当然dolphin不可能learn，所以不就加强了呀，求高手答为什么
（答案是B）