Select from options: Continue writing the next sentence.

A man is using an elliptical trainer while standing. Then a woman sits on it as she uses it in another fashion. it

Select from the following.
 a). 's then shown under an exercise machine.;
 b). switches between the two as they exercise.;
 c). is the same machine, next to the man on the treadmill.;
 d). then shows the replay of the first woman.;
Answer:
b).