Recently, Amy Went on a Diet to Lose 5 Pounds

Recently, Amy went on a diet to lose 5 pounds. Amy lost the weight she wanted to, but found it hard to stop dieting even though she had met her weight-loss goal. Amy ate even less than before and became increasingly focused on losing even more weight. Amy began to look extremely thin and her weight dropped well below what was average for someone her age and height. It is likely that Amy has developed:

A) bulimia nervosa.
B) anorexia nervosa.
C) binge eating disorder.
D) purging disorder.