Frequently and Without Warning, Images of Germs Pop into Corbin's

Frequently and without warning, images of germs pop into Corbin's mind, and he feels an irresistible urge to stop whatever he is doing, run to a sink, and wash his hands repeatedly. After washing his hands, he feels safe and comfortable; during an attack he is convinced that he will die if he is not allowed to wash his hands. Corbin appears to suffer from a(n)

A) physiological dependence on water.
B) personality disorder.
C) psychotic disorder.
D) obsessive-compulsive or related disorder.