Answer:
The correct answer would be "It helps build muscles".
Proteins are termed as the building blocks of the body as they mainly serve as the structural component of the cells including muscle cells.
For example, muscle cells are mainly composed of myosin and actin which are protein in nature.
In addition, they serve many other roles in an organism such as immunoglobins, protein or amino acid hormones, enzymes, signal transduction et cetera.