Which of the following is considered a macronutrient?

Protein is considered a macronutrient because it is one of the primary components necessary for maintaining and repairing body tissues, supporting immune function, and serving as an energy source. Macronutrients, which include protein, carbohydrates, and fats, are required in larger amounts compared to micronutrients, which are vitamins and minerals that the body needs in smaller quantities.

Protein plays a vital role in various bodily functions, such as muscle building, enzymatic reactions, and hormone production. Unlike vitamins and minerals, which are classified as micronutrients, protein provides the essential amino acids that the body cannot synthesize on its own, making it crucial for overall health and growth. Therefore, protein's significance in sustenance and physiological functions solidifies its category as a macronutrient.

In contrast, vitamin K and iron are classified as micronutrients. They are essential for health but are required in much smaller amounts. Calcium, although critical for bone health and various bodily functions, is also categorized as a mineral rather than a macronutrient.