Which physical quantity only has magnitude and no direction?

The correct choice is scalar because a scalar is defined as a physical quantity that is characterized solely by its magnitude, meaning it has a numerical value but does not have a direction associated with it. Common examples of scalar quantities include temperature, mass, speed, and energy.

In contrast, other listed terms are vectors, which are defined by both magnitude and direction. For instance, acceleration is a vector quantity because it describes how quickly an object changes its velocity and includes a directional component. Similarly, force is a vector quantity as it has both magnitude and direction in which it acts.