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: The dolphins often exhibit complex new responses to the hand signal.
B: Some of the behaviors mentioned are exhibited by dolphins in their natural habitat.
C: Dolphins do not interact with humans the way they interact with one another.
D: The dolphins are given food incentives as part of their training.
Choose A, B, C or D as your solution.
A