The outlet of a bicycle pump is used to inflate a football as illustrated in the diagram above. Why does the pressure of the air inside the pump increases as the pimp handle is slowly pushed downward at constant temperature?

• A.momentum of the air molecules are increased
• B.volume occupied by the molecules are increased
• C.frequency of collision of the air molecules with the walls of the pump is increased
• D.more air molecules are collidin with one another in the system