Which of the following describes a scalar quantity?

A scalar quantity is defined as a measurement that is fully described by a magnitude alone, without any consideration for direction. This characteristic distinguishes it from vector quantities, which require both magnitude and direction for their complete description. For example, temperature, mass, and distance are all scalar quantities, as they do not involve any directional component.

In contrast, the other options involve direction in some capacity, which does not apply to scalar quantities. A quantity that involves direction and magnitude is defined as a vector, and terms like "vector in motion" and "rotating point" imply the presence of directionality, further differentiating them from scalars. Therefore, the understanding that scalar quantities focus solely on magnitude is what makes the second option the appropriate answer.