The correct answer is D. Velocity
Step-by-step explanation:
The concept "velocity" is used in mechanics and other field that study motion to describe the change of position an object has based on the speed which refers to how fast an object goes and the direction of motion which is determined by the cardinal point such as north, east, west or south the object moves. This implies in velocity units that express speed such as miles per hour or kilometers per hour along with words that show direction such as north, northeast or southwest are used to study the movement of a body and therefore the statement "20 miles per hour north" that includes speed (20 miles) and direction (north) is a clear example of velocity.