John Rapidly Pulls a Plunger Out of a Cylinder

Multiple Choice

John rapidly pulls a plunger out of a cylinder.As the plunger moves away,the gas molecules bouncing elastically off the plunger are

A) rebounding at a higher speed than they would have if the plunger weren't removed.
B) rebounding at a lower speed than they would have if the plunger weren't removed.
C) rebounding at the same speed as they would have if the plunger weren't removed.
D) Whether they speed up or slow down depends on how fast the plunger is removed.