Question

which atoms are in all carbohydrates?
carbon, hydrogen, oxygen
carbon, phosphorus, hydrogen
oxygen, hydrogen, nitrogen
carbon, nitrogen, oxygen

Explanation:

Carbohydrates are organic compounds. By definition, they are composed of carbon ($C$), hydrogen ($H$), and oxygen ($O$). Phosphorus ($P$) is not a component of carbohydrates (it is found in nucleic acids like DNA). Nitrogen ($N$) is not in carbohydrates (it is in proteins and nucleic acids). So we check each option against the known composition of carbohydrates.

Answer:

carbon, hydrogen, oxygen