Final answer:
A nutrient requirement is the minimum amount of a nutrient needed for nutritional health. Nutrients are essential molecules that the body uses to function properly and maintain good health. There are three classes of nutrients: water, energy-yielding and body-building nutrients, and micronutrients (vitamins and minerals).
Step-by-step explanation:
A nutrient requirement is the smallest amount of a nutrient that maintains a defined level of nutritional health. Nutrients are molecules which the body uses to function appropriately and stay in a healthy condition. They are divided into three classes: water, energy-yielding and body-building nutrients, and micronutrients (vitamins and minerals).