This is a test of commonsense with single/multi-choices. Complete the next sentence:

People workout on a fitness machine pulling a strings on a rod and going back and forth. A man folds a fitness machine in a gym. then

Choose from: A). , a woman stands on a rope and begins to swing a rod.; B). , a man make workouts in a fitness machine.; C). , people walks to a beach and sit on chairs.; D). , people workout bungee jumping in sand as they keep the rod in their hands as if to jump.;
The answer is:
B).