What is the primary function of carbohydrates in the body?

The primary function of carbohydrates in the body is to provide energy. Carbohydrates are one of the three macronutrients, along with proteins and fats. They are made up of sugar molecules, which the body can quickly convert into glucose, the primary energy source for cells. This energy is crucial for various bodily functions, including physical activities, metabolism, and maintaining core physiological processes.

The body's cells prefer glucose for energy, as it is a readily accessible fuel source, particularly for high-intensity activities. Additionally, carbohydrates play a role in sparing protein for its primary function of building and repairing tissues, rather than using it as an energy source. While proteins and fats can also provide energy, carbohydrates are typically the body's first choice, especially during exercise and exertion.

Other choices refer to functions of different biological systems or nutrients. For instance, building muscle is primarily the role of protein, regulating body temperature involves several physiological mechanisms and does not directly relate to carbohydrates, and transporting oxygen is mainly the function of hemoglobin in red blood cells, which is not related to carbohydrates' primary role.