Which of the following defines a nutrient?

A nutrient is best defined as a substance that provides essential nourishment for growth, maintenance, and overall health. Nutrients are crucial for various biological functions, including building and repairing tissues, regulating bodily processes, and producing energy. In food, nutrients include macronutrients such as carbohydrates, proteins, and fats, as well as micronutrients like vitamins and minerals. The importance of nutrients in promoting growth highlights their role in the diet and overall health of organisms.

Choices related to energy sources, methods of digestion, and metabolic processes, while relevant to nutrition, do not capture the broader definition of what a nutrient fundamentally is. Energy sources refer specifically to how nutrients are utilized for energy, digestion pertains to the breakdown of food, and metabolic processes involve the chemical reactions that occur in the body—none of these effectively encapsulate the essence of what constitutes a nutrient on its own.