The correct answer is C) depressive disorder.
The other options of the question were A) bipolar disorder. B) schizophrenia. D) obsessive-compulsive disorder
Carter is a veteran officer who has been through the Vietnam War. His experiences in combat, the death of his colleagues, and his own hardships have affected his mental and physical health. He feels guilty that he could not save many of his colleagues during the war and blames himself for their death. Carter is most likely to develop a depressive disorder due to his wartime experiences.
Depressive disorders made the patient dive deeply in sadness during prolonged periods that impede the person to have a normal life. These people showed no interest in doing any kind of activity and they lose interest to help themselves or to accept outside help. That is what Carter is about to suffer due to its many difficult and painful memories.