What are hydrocarbons composed of?

Hydrocarbons are organic compounds that consist exclusively of hydrogen and carbon atoms. This definition stems from the fundamental structure of hydrocarbons, where carbon atoms can bond together to form a backbone, with hydrogen atoms filling the remaining available bonds. This composition is vital in various applications, including fuels and the production of different organic chemicals.

The other choices do not accurately represent the composition of hydrocarbons. For instance, the inclusion of oxygen and nitrogen, or sulfur, implies other types of compounds rather than hydrocarbons. Options mentioning oxygen would relate more to alcohols or acids, while including sulfur might refer to thioethers or other sulfur-containing compounds. Consequently, the correct answer highlights the simplicity yet fundamental nature of hydrocarbons in organic chemistry.