Which of the following describes a vector quantity?

A vector quantity is defined as one that possesses both magnitude and direction. This means that when we describe a vector, we not only indicate how much of the quantity there is (the magnitude) but also in which direction it is acting. Common examples of vector quantities include displacement, velocity, and force, where knowing the direction in addition to the amount is essential for a complete understanding of the quantity's effects.

In contrast, a quantity that has only magnitude would be a scalar quantity, which does not include directional information. Additionally, while certain quantities can remain constant or take on negative values, this does not pertain specifically to the characteristics defining vector quantities. Therefore, the defining feature of vector quantities is their combination of both magnitude and direction, making the correct choice clear.