In a transposition experiment discussed in class, chimpanzees were reinforced for choosing a medium gray card over a light gray card. Then, in Phase 2, they were given a choice between medium gray and dark gray. In the second phase, the cognitive view was that the animals would choose the gray card based on the concept of learning:

dark grey, relational                                  

Explanation:

Relational learning: In psychology, the term "relational learning" is described as one of the different forms of learning that occurs in the context where there's a possibility of a relationship that exists between learning examples or where the given examples might have a "complex" internal structure i.e, possesses various components and there's a possibility of having a relationship between mentioned components.

In the question above, the given statement signifies the relational learning.