Stacy becomes stressed easily, and often copes by eating an entire carton of ice cream, a bag of potato chips, a pound of chocolate and drinks a two-liter bottle of soda. She then forces herself to vomit so that she doesn't absorb all of those calories. Stacy is most likely suffering from:

A. bulimia nervosa.
B. anorexia nervosa.
C. obesity.
D. ghrelin deficiency syndrome.