Answer: B. If an object's velocity is changing,it's either experiencing acceleration or deceleration.
Acceleration is defined as the rate at which an object changes its velocity. This implies that if an object is changing it's velocity it is experiencing acceleration/ deceleration.
Acceleration is a vector quantity that has both a magnitude and time.
It is represented as
Acceleration= change in velocity/time.
The SI unit for acceleration is m/s^2