Which of these is NOT a macronutrient?

The correct answer is vitamins because they are classified as micronutrients, not macronutrients. Macronutrients include fats, carbohydrates, and proteins, which are the major nutrients needed in larger amounts to provide energy and support bodily functions.

Fats serve as a concentrated source of energy, play a crucial role in cell structure, and are essential for absorbing fat-soluble vitamins. Carbohydrates are the body's primary energy source, especially for the brain and during physical activity. Proteins are vital for growth, repair, and maintenance of body tissues and are also involved in numerous metabolic processes.

Vitamins, on the other hand, are needed in smaller quantities and are essential for various biochemical functions and maintaining health, but they do not provide energy like macronutrients do.