What energy-producing substances are contained in almost all foods?

Carbohydrates, proteins, and fats are the primary macronutrients found in almost all foods that provide energy to the body. Each of these substances has distinct roles and mechanisms for energy production.

Carbohydrates are typically the body's preferred source of energy because they can be quickly converted into glucose, which is essential for providing immediate energy to cells. They are found in foods like grains, fruits, and vegetables. Proteins, while primarily used for tissue repair and building, can also be metabolized for energy when necessary, especially in low-carbohydrate diets. Sources of protein include meat, dairy, legumes, and nuts. Fats are also a crucial energy source, providing a concentrated form of energy and being necessary for the absorption of certain vitamins. They come from oils, butter, avocados, and fatty fish.

The other answer choices do not focus exclusively on the main energy-producing macronutrients. For instance, while calories are a measure of energy, they do not themselves constitute a substance. Similarly, nutrients encompass a broader category that includes vitamins and minerals but do not specifically highlight the primary macronutrients responsible for energy production. Therefore, the option that identifies carbohydrates, proteins, and fats correctly highlights the essential energy-providing substances found