What are comets made of?

A. Chunks of rock and gas
B. Chunks of Rock with many craters
C. Ice, gas, and dust
D. Pieces of rock and dust

correct me if I'm wrong but I think that B is an asteroid and that D is incorrect so hope that helps limit it to A and C. (I know it's not D because I pressed it the first time and got it wrong, but still feel free to correct me if I'm in fact wrong, Also this is a science, more astronomy, question but doesn't have a "pick a subject" science as an option so sorry to which category I choose to put this under, again my apologies.)

Explanation:

Comets is one of the main types of space rocks. Recent researchers has termed Comets as 'dirty snowballs' of space, that contains ice, rock, gas and dust. The solid center of the comet is less than 10 kilometers across.

Comets are believed to have originated beyond Neptune and Pluto. It is called the Oort Cloud that surrounds the solar system.

It carries carbon dioxide, methane, ammonia, and many more gases. According to Astronomers, comets are assumed to be the leftovers of the material that was initially the part of solar system about billion years ago.

whichever one it is, it's definitely not one that you included on the list you provided.