Which of the following is NOT a macronutrient?

To understand why the answer is "B," it’s important to define what macronutrients are and how they differ from micronutrients. Macronutrients are the nutrients that the body requires in larger amounts for energy, growth, and bodily functions. They include carbohydrates, proteins, and fats. These substances provide the energy necessary for daily activities and physical health.

Micronutrients, on the other hand, consist of vitamins and minerals that are essential for various bodily functions but are required in smaller quantities. They play crucial roles in processes such as metabolism, immunity, and bone health, but they do not provide energy themselves.

In this context, fats, carbohydrates, and proteins are all classified as macronutrients because they contribute to the body's caloric intake and are essential for the energy required for various physiological processes. Therefore, identifying micronutrients as the correct choice is based on the understanding that they are not included in the category of macronutrients.