Answer the following question given this paragraph: 

You can tell that this sponge is saturated with water because when it is squeezed, the water pours out. When something is saturated with water, it already holds as much water as possible. Compounds called hydrocarbons, which contain only carbon and hydrogen, can also be saturated, but not with water.


Q: What compounds contain only carbon and hydrogen?


A:
hydrocarbons