It is one thing to acquire a behavior in initial form and quite another to subsequently

refine the behavior so that it eventually matches the target behavior. This process of
acquisition can occur on one's own, without the intervention of others.

It occurs because
successive approximations to the target behavior produce
a. covert CSs.
b. automatic conditioned reinforcement.
c. habituation.
d. automatic shaping.
e. covert response chains.

b. automatic conditioned reinforcement.