Comets are icy bodies because they originate in areas beyond Neptune.
Option a
Step-by-step explanation:
Comets are icy, “small solar system” bodies that, warms up and begins to release gases or dust when it passes close to the Sun. The nucleus of a comet is made up of an combination of rock, dust, water ice, and frozen carbon dioxide, carbon monoxide, methane, and ammonia while the surface of the nucleus is generally dry, dusty or rocky.
They are often called as dirty snowballs because of their physical appearance and due to the fact that these Short-period comets originate in the Kuiper belt that lies beyond the orbit of Neptune. Comets have an icy body because they originate from a disk-shaped band of icy objects known as the “Kuiper Belt” that lies just “beyond Neptune's orbit”, with gravitational interactions with the outer planets dragging these bodies inward.