Which of the following is considered a trace mineral?

Trace minerals are essential nutrients that the body needs in very small amounts to function properly. Among the options provided, iron is recognized as a trace mineral. It plays a crucial role in various bodily functions, most notably in the formation of hemoglobin, which is vital for transporting oxygen in the blood.

In contrast, the other minerals listed—calcium, potassium, and magnesium—are categorized as major minerals or macrominerals. These are required by the body in larger amounts and serve important functions, such as maintaining bone health (calcium), regulating fluid balance and muscle contractions (potassium), and supporting nerve function and energy production (magnesium). Understanding these classifications helps clarify the distinct roles that different minerals play in nutrition and overall health.