What are comets primarily made up of?

Comets are primarily made up of dust and frozen gases, which is often referred to as "dirty snowballs." This composition includes a mix of water ice, carbon dioxide, ammonia, and other volatile compounds, along with various types of rock and dust particles that provide their structure. When comets approach the sun, the intense heat causes the frozen gases to vaporize, creating a glowing coma and often a tail that is pushed away from the sun by solar wind. This process illustrates the distinctive features of comets, setting them apart from other celestial objects like asteroids, which are mainly composed of rocky materials and metals.

The options that mention rocky material, metals, solid rock, or meteoroids primarily focus on components and bodies that do not capture the unique characteristics of comets. Comets are specifically noted for their icy nature and the interplay between their dust and gas components, which is essential in understanding their behavior and visual phenomena in the solar system.