The subunits (building blocks) of proteins are

A. nucleotides

B. phospholipids.

C. amino acids.

D. carbohydrates.

C. amino acids.

Explanation:

Amino acids are organic molecules that combine to form proteins whereas a nucleotide is an organic compound that combines a sugar molecule and a phosphate. Phospolipids are fatty acids that also contain a phosphate molecule and lastly carbohydrates which are also known as saccharides are made up of Carbon, Hydrogen and Oxygen atoms.