Which of the following is a trace mineral?

• A. Copper
• B. Sodium
• C. Phosphorus
• D. Potassium

Answer: (A)

Copper is a trace mineral because it’s needed in only small amounts by the body, yet it plays several essential roles. As a cofactor for enzymes such as ceruloplasmin, it helps with iron metabolism, copper-containing enzymes support connective tissue formation, and some copper-containing enzymes are involved in antioxidant defenses. Because the body requires only trace amounts—much less than other minerals—it’s classified with other trace minerals rather than as a macromineral.

In contrast, the other minerals listed are macrominerals, required in much larger daily amounts. Sodium and potassium are key electrolytes that maintain fluid balance and nerve function, while phosphorus is important for bone and energy metabolism. Their larger daily needs reflect the broad physiological roles they support.