Final answer:
The true statement about circular motion is that it is always planar. Circular motion requires centripetal force, and centripetal acceleration is directed toward the center of the circle, not outward.
Step-by-step explanation:
The question asks for the true statement about circular motion. The correct option in this case is D: Circular motion is always planar. This is because circular motion, by definition, occurs in a plane, which can be described as a flat, two-dimensional surface.
In contrast to the other options provided: A is incorrect because while the speed remains constant in uniform circular motion, velocity is not constant since it's a vector quantity that depends on both magnitude and direction. B is incorrect because a centripetal force is required to keep the object moving in a circle. This force is directed toward the center of the circle, providing the necessary centripetal acceleration. C is incorrect as the acceleration in circular motion is not directed outward; it is the centripetal acceleration that is directed inward toward the center of the circular path.