What is a key characteristic of the asteroid belt?

The asteroid belt is primarily composed of numerous small, rocky bodies, which vary in size from tiny pebbles to larger asteroids that can be hundreds of kilometers across. These rocky remnants are considered to be leftover building material from the early solar system that never coalesced into a full planet due to the gravitational influence of nearby Jupiter. The large distances between these bodies and their generally irregular shapes also contribute to the overall characterization of the belt as a region filled with rocky debris rather than massive bodies or gas.

The other characteristics listed do not accurately describe the asteroid belt: it does not contain significant amounts of ice or water, as that is more representative of comets or certain regions beyond the asteroid belt. Moreover, it does not include large gas giants; those are found in different regions of the solar system. Although there are dwarf planets in the solar system, none of the recognized ones reside in the asteroid belt itself. Thus, the key distinguishing feature of the asteroid belt aligns with the composition of small rocky bodies.