Which of the following describes a vector quantity?

Momentum is a vector quantity because it has both magnitude and direction. In physics, a vector quantity is defined not only by how much there is (the magnitude) but also by the direction in which it acts. Momentum is calculated as the product of an object's mass and its velocity, where velocity itself is a vector. This means that when discussing momentum, we need to consider in which direction the object is moving, in addition to how fast it is moving.

In contrast, mass is a scalar quantity that only has magnitude and no direction. Speed is similar; it tells us how fast an object is moving, but it does not indicate the direction of that motion, making it a scalar as well. Energy, too, is represented as a scalar quantity, as it measures the capacity to do work without the implication of direction. Thus, among the listed options, only momentum appropriately embodies the defining characteristics of a vector quantity.