<prompt> Most common major symptom of obsessive-compulsive disorder isCompulsive washing of handCompulsive thinking about sameCompulsive checkingObsessive precision  <response>: Compulsive washing of hands is the commonest type. Here obsession is of contamination with di, germs, body excretions and the like. Compulsion is washing hands or the whole body, repeated many times a day. It usually spreads on to washing clothes, washing of bathroom, door knobs, and personal aicles gradually Ref: a sho textbook of psychiatry, Niraj Ahuja,7th edition, pg no 95 