The correct option is B Activity
Activity means busy or vigorous action or movement. The opposite of activity is lethargy, or a lack of energy and enthusiasm. Hence, Option B is correct. Among the rest of the options, intelligence means the ability to acquire and apply knowledge and skills, sharpness means the quality or state of being sharp, quickness means the quality of moving fast or doing something in a short time.These do not express this antonym, hence incorrect.