What is the definition of nutrition?

The correct definition of nutrition is the process of providing or obtaining the food necessary for health and growth. This encompasses a broad understanding of how the body utilizes food for energy, maintenance, and development. Nutrition involves not only the intake of food but also the biological and physiological processes that convert food into usable energy and nutrients that support bodily functions.

While the other options touch upon aspects related to food and dietary components, they do not fully capture the comprehensive nature of nutrition. The measurement of energy in food is a specific aspect of nutritional science but lacks the holistic view that encompasses all aspects of how nutrients support health. Similarly, the total caloric value of a food item only addresses the energy content without considering the nutritional quality or the role of various food components in overall health. Finally, while dietary supplements are important in certain contexts, they represent just one aspect of nutrition rather than a complete definition. Thus, option A accurately summarizes the essence of nutrition as it relates to health and growth.