Answer the following question given this paragraph: 

Hydrocarbons are compounds that contain only carbon and hydrogen. The carbon atoms in hydrocarbons may share single, double, or triple covalent bonds. Unsaturated hydrocarbons contain at least one double or triple bond between carbon atoms. They are classified on the basis of their bonds as alkenes, aromatic hydrocarbons, or alkynes.


Q: Hydrocarbons are made up of carbon and what else?

 Choices:

- silicon

- nitrogen

- helium

- hydrogen

A:
hydrogen
