Which of the following describes an object that cannot float?

An object described as "sink" indicates that it is unable to float and instead descends to the bottom when placed in a fluid. This typically occurs when the object's density is greater than that of the fluid it is in. For instance, a dense stone or metal will sink in water because it cannot displace enough fluid to counteract the force of gravity acting on it.

In contrast, the other terms relate to either floating or moving in a fluid but do not specifically convey the inability to float. "Float" signifies that an object is capable of remaining on the surface of a liquid, "drift" refers to the gentle movement of an object in water without sinking or rising abruptly, and "rise" implies that an object is moving upward, which is typically associated with objects that are less dense than the surrounding fluid and thereby can float.