Question

which element is present in all amino acids, but not necessarily in fats or carbohydrates?
phosphorus
hydrogen
nitrogen
oxygen

Explanation:

Amino - acids have an amino group (-NH₂) which contains nitrogen. Fats and carbohydrates are composed mainly of carbon, hydrogen, and oxygen and do not necessarily have nitrogen. Phosphorus is not present in all amino - acids. Hydrogen and oxygen are present in fats and carbohydrates as well as amino - acids.

Answer:

C. nitrogen