Which component constitutes the smallest percentage of muscle?

The correct choice is sodium because, while sodium is an essential mineral found in all bodily fluids and plays a critical role in muscle function and nerve transmission, it constitutes only a small percentage of the overall composition of muscle tissue.

Muscle tissue is primarily composed of water, which makes up a significant portion, typically around 70-75% of muscle mass. Protein is another major component, accounting for about 20-25%, as it is crucial for muscle structure and function, including contraction. Potassium, essential for muscle contraction and maintaining fluid balance, also exists in higher concentrations compared to sodium within muscle cells.

This explains why sodium, while important for muscle health, represents the smallest percentage compared to these other vital components.