Robert is trying to stop drinking alcohol, but his anxiety levels increase dramatically when he stops. If he increases his alcohol consumption to cope with this anxiety, his behavior could most readily be explained by the _________.

a. self-medication hypothesis.

b.conclusion that his anxiety and his alcohol problem come from some shared factors.

c. conclusion that one or more of his family members must also have an alcohol problem.

d. conclusion that he must be under a great deal of stress.