How is velocity defined in the context of motion?

Velocity is defined as the rate at which an object changes its position, and it is a vector quantity, which means it has both magnitude and direction. Answer D captures this concept effectively by highlighting that velocity involves both a rate of speed and ensures the context of movement from one position to another.

While speed alone refers to how fast an object is moving regardless of direction, velocity incorporates direction, providing a more complete description of the motion. This distinction is crucial, as two objects may have the same speed but very different velocities if they are moving in different directions.

The other definitions do not accurately encompass the concept of velocity, as they either omit direction or confuse velocity with speed and other related terms. Therefore, D is the most comprehensive and correct definition of velocity in the context of motion.