What are asteroids primarily composed of?

Asteroids are primarily composed of a mixture of rock, metal, and various types of dust. The correct answer reflects the dominant materials found in most asteroids, particularly those located in the asteroid belt between Mars and Jupiter. They are primarily rocky in nature, which aligns with option A, encompassing both solid rock and the small fragments and dust that may be found on their surfaces.

While other options include materials like gas and ice, these are not generally representative of the composition of asteroids. For example, gas is more common in larger celestial bodies like gas giants rather than in smaller solid bodies like asteroids. Ice can be found in some icy bodies in the outer solar system, but asteroids are predominantly rocky or metallic, hence the choice of ice, rock, and dust as the most accurate description of their composition.