I think the correct answer from the choices listed above is option A. Wave motion is a movement of energy through space or a medium . Some waves are visible light waves, heat waves, sound waves and the like. Hope this answers the question.
Work = (force) x (distance)
Work = (21 Newtons) x (9 meters) = 189 Joules
Power = (work done) / (time to do the work)
Power = (189 Joules) / (3 sec)
Power = (63 watts/sec)
Power = 63 watts (D)