Planets without atmospheres usually have many craters caused by meteoroids are usually warmer than planets which have atmospheres cannot reflect the sun's light back into space are usually made of hydrogen and helium

Planets without atmospheres usually have many craters caused by meteoroids. 

Atmospheres give a layer of protection to the planets. Mercury for example has a lot of craters and it is a planet that does not have an atmosphere. Although it is hot, the heat is caused by its distance to the sun and not necessarily due to the lack of atmosphere. 

The correct answer would be b