Which statement is true about the atomic mass? A)It is always lower than the atomic number.

B)It is never greater than the atomic number.

C)It can be greater than the atomic number.

D)It always equals the atomic number.

Their acceleration is zero. therefore the correct answer is C.

Acceleration is defined as the rate of change of velocity, since the runner is moves with the constant velocity, therefore their will be no change in its velocity with respect to time, or the rate of change of velocity (acceleration) is zero.