What is the difference between speed and velocity?
A. Speed measures an object's change in position, while velocity measures an object's change in position per unit time.
B. Velocity measures an object's rate and direction of motion, and speed measures rate only.
C. Velocity and speed both measure an object's change in position, but velocity only depends upon the object's speed.
D. Speed measures an object's change in position per unit time, while velocity measures an object's change in speed per unit time.