A 19-year-old female is admitted to the emergency department after being found unconscious. Her blood pressure is 82/50 mm Hg. She is 5'4" tall and weights 35.8 kg. She appears dehydrated and malnourished. After regaining consciousness, she reports that she has had trouble eating lately and can't remember what she ate in the last 24 hours. She also states that she has had irregular menstrual period for the past one year. She is convinced she is fat and refuses food. The nurse suspects that she is a case of
1. Bulimia nervosa
2. Schizophrenia
3. Reactive depression
4. Anorexia nervosa