What the food polymer used to form new body polymer

The answer to this question would be: protein

There are 3 major macromolecules that are found in food: carbohydrate, lipid, and protein. The molecule that is used to made body cells is mostly amino acids. Protein is the polymer form of the amino acid which mean protein was made from multiple amino acids. When digested, protein will be cut into smaller amino acids.

Ithink the answer is d.