Chiara, a 14-year-old, is of average height but weighs only 80 pounds. She has lost 30 pounds over the last six months by eating very little and running five miles a day. She is determined not to become overweight and ignores her parents' suggestion that she should eat well-balanced meals. Chiara suffers from________A. Bulimia nervosa.B. Obesity.C. An abnormally low set point.D. Anorexia nervosa.E. Hypermetabolism.