Final answer:
Velocity is the vector quantity among the options provided; it is defined by both its magnitude (speed) and its direction of motion.
Step-by-step explanation:
Out of the given options, velocity is a vector quantity. This is because a vector quantity must have both magnitude and direction, which matches the definition of velocity. Velocity is used to describe how fast an object is moving and in which direction. For example, saying a car is traveling at 60 miles per hour to the north provides both a speed (magnitude) and a direction, making it a vector.
Other options like mass, temperature, and distance are scalar quantities. These have magnitude but lack direction. Mass is simply a measure of how much matter an object contains. Temperature measures the warmth or coldness of an object or environment. Distance refers to the measure of how much ground an object has covered during its motion, but it doesn't provide the direction of that motion.
To further illustrate, consider another vector quantity: displacement. Displacement is a vector that describes the change in position of an object. It is defined by both magnitude (the shortest distance from the initial to the final position) and direction (from the start point to the end point). For example, if you walk 5 meters east, your displacement is 5 meters to the east.