Which of the following is a primary source of energy for the body?

Carbohydrates are considered a primary source of energy for the body because they are easily broken down into glucose, which is the main fuel used by cells for energy. When consumed, carbohydrates are digested and converted into glucose, which can be immediately utilized by the body's cells for energy or stored for later use in the form of glycogen in the liver and muscles. This quick conversion makes carbohydrates an efficient energy source, especially during physical activities or exercise.

Proteins, while valuable for growth and repair of tissues, do not primarily serve as an energy source. Instead, their main function is to provide the building blocks for the body’s structures, such as muscles, enzymes, and hormones. Fiber is not broken down for energy; rather, it aids in digestion and supports gut health. Vitamins play crucial roles in various biochemical processes in the body but do not provide energy directly. Thus, carbohydrates are the most significant and immediate source of energy within the diet.