Experimental studies in which animals and humans receive supplements of human growth hormone have shown that their long-term use is safe, and their health benefits are permanent.

Which of the following statements is true?

A) Many parts of the brain appear to have no useful function in today's world. B) Losses of small areas of certain parts of the brain rarely cause devastating, often permanent, losses of function. C) All the brain areas become active on brain scans at one time or another as we think, feel, and perceive. D) Every part of the brain has a redundant backup, which is why brain injuries are so rarely serious.

When those who underwent a severe ordeal are now recalling and reliving the event and having associated physical symptoms, they are experiencing

a. unresolved mild stress. b. posttraumatic stress disorder. c. hardiness. d. learned helplessness. e. immunosuppression.