How is "nutrient" best defined?

The term "nutrient" is best defined as a substance or ingredient that provides nourishment. Nutrients are essential for the body's growth, maintenance, and overall health. They include a variety of substances such as carbohydrates, proteins, fats, vitamins, and minerals that play vital roles in bodily functions.

Understanding this definition is crucial as it captures the breadth of what constitutes a nutrient. Each type of nutrient has specific functions—but all contribute to the body's energy supply, support metabolic processes, and help in the repair and maintenance of body tissues. This comprehensive view emphasizes the importance of a balanced diet that includes all these nutrient types for optimal health.

The other options do not encompass the complete definition of "nutrient." For instance, defining it strictly as a type of mineral found in water is overly narrow. Similarly, stating it as an organic compound lacking in proteins excludes many essential nutrients. Lastly, describing it as a chemical ability to aid digestion does not accurately reflect the broader role of nutrients in providing nourishment beyond just aiding digestion.