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.)

Comets are made of Chunks of rock, gas, Ice, and dust. The Answer is A and C.

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.

  sequence  is a continuous and distinctive band of  stars  that appears on plots of stellar  color  versus  brightness. these color-magnitude plots are known as  hertzsprung–russell diagramsafter their co-developers,  ejnar hertzsprungand  henry norris russell. stars on this band are known as  main-sequence stars  or  dwarf stars. these are the most numerous true stars in the universe, and include the earth's  sun.after condensation and ignition of a star, it generates  thermal energy  in its dense core region through  nuclear fusion  of  hydrogen  into  helium. during this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and age. the cores of main-sequence stars are in  hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of  gravitational collapse  from the overlying layers. the strong dependence of the rate of energy generation on temperature and pressure to sustain this balance. energy generated at the core makes its way to the surface and is radiated away at the  photosphere. the energy is carried by either  radiation  or  convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.the main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. stars below about 1.5 times the  mass of the sun  (1.5  m☉) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the  proton–proton chain. above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of  carbon,  nitrogen  and  oxygen  as intermediaries in the  cno cycle  that produces helium from hydrogen atoms. main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. below this mass, stars have cores that are entirely radiative with convective zones near the surface. with decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases. main-sequence stars below 0.4  m☉undergo convection throughout their mass. when core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.in general, the more massive a star is, the shorter its lifespan on the main sequence. after the hydrogen fuel at the core has been consumed, the star  evolves  away from the main sequence on the hr diagram, into a  supergiant,  red giant, or directly to a  white dwarf.