Elmer,the Owner of an Auto Service Station,suddenly Began Smashing the Front

Elmer,the owner of an auto service station,suddenly began smashing the front fenders and hoods of two customers' cars.When asked why,he excitedly explained that he was transforming the cars into "real racing machines." When an employee tried to restrain him,he shouted that everybody was fired and quickly began breaking the car windows.Elmer is exhibiting symptoms of

A) depression.
B) disruptive mood dysregulation disorder.
C) rumination.
D) mania.