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 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.

Please dont cut sentences in half. Now it's readable!