Velocity is defined as:

Velocity is defined as the rate at which an object changes its position. This encompasses not only the speed of the object but also the direction in which it is moving. Velocity is a vector quantity, meaning it has both magnitude (how fast something is moving) and direction (the path it is taking). For example, if a car is traveling east at 60 miles per hour, its velocity is 60 miles per hour east. This distinction is crucial because speed alone does not provide information about direction, which is essential for understanding motion in physical contexts.

The other options, while related to the motion of an object, do not capture the full essence of velocity as a vector. The first choice discusses total distance and time, which refers to average speed, another concept related to motion. The second choice mentions the rate of speed but doesn't specify direction, falling short of the complete definition of velocity. The last option focuses solely on speed in a straight line, omitting the key aspect of direction that is vital to understanding velocity.