Milford Retired from His Job Several Years Ago, and Lately

Milford retired from his job several years ago, and lately he has been feeling lethargic, unhappy, and useless. He does not want to work in the garden or go fishing with his friends. His wife and her friends believe that he is just moody and that everyone will just have to put up with his behaviour. It is likely that

A) every older person feels this way after retiring.
B) in time, he will likely get past his negative feelings.
C) his behaviour reflects a long-standing mental illness that was not apparent until now.
D) if he became involved in other activities, his mood would likely improve.
E) he is probably suffering from a mood disorder and could benefit from treatment.