Studies by Keller and Marian Breland found that many animals exhibit instinctive drift. What does this mean?

a. The animals studied would learn skills through reinforcement, and they remained that way no matter how much reinforcement they were given.

b. The animals studied could not learn any skills even with the use of reinforcement.

c. The animals studied would learn skills through reinforcement but eventually revert to their genetically controlled patterns of behavior.

d. The animals studied could only learn skills similar to those found in the wild.