What describes a nongaseous substance that moves and flows freely, assuming the shape of its container?

A nongaseous substance that moves and flows freely while assuming the shape of its container is best described as a liquid. Liquids have distinct properties that differentiate them from solids and gases. Unlike solids, which maintain a fixed shape due to closely packed molecules, liquids have molecules that are less tightly held together, allowing them to move around freely. This mobility enables the liquid to take the shape of any container in which it is placed, filling the bottom of the container while maintaining a relatively constant volume.

In contrast, gases expand to fill their containers completely and do not have a defined volume or shape, which is a characteristic different from that of liquids. Solids, on the other hand, have a defined shape and volume due to tightly packed molecules that do not flow. Aerosols, while containing liquid substances dispersed in a gas, do not represent a bulk liquid on their own. Therefore, the definitive properties of a liquid—its ability to flow and take the shape of its container—make it the correct answer.