Two students go to play basketball. They notice the ball is flat (it won't bounce). They decide to pump it up with air. After it is pumped with air, will the ball have more, less, or the same amount of mass as before air was added? A. The ball has less mass after being pumped with air.

B. Cannot determine unless we measure the mass.

C. The ball has more mass after being pumped with air.

D. The ball has the same amount of mass after being pumped with air.

Justify your answer