Answer: D. Sleep.
Words with the word root dorm will always have a meaning related to inactiveness and sleep. This is so because dorm is a Latin word meaning asleep, dormant, inactive, not growing, etc. this makes more sense when words containing dorm are analyzed. Words like dormant, meaning lying asleep, dormitory; a large bedroom in an institution for a large number of people, dormancy; not having motion or being static.