Which of the following is classified as a trace mineral?

Selenium is classified as a trace mineral because it is required by the body in very small amounts to maintain proper health. Unlike major minerals, which are needed in greater quantities (like calcium, sodium, and magnesium), trace minerals play significant roles in various biological processes despite their smaller required intake. Selenium is important for antioxidant defense, immune function, and thyroid hormone metabolism.

In contrast to selenium, calcium, sodium, and magnesium are categorized as major minerals, which the body requires in larger amounts to support functions such as bone health, fluid balance, and muscle function. Understanding the distinction between trace and major minerals is crucial for appreciating their roles in nutrition and health.