Biology

The correct answer is A.Carbohydrates.

A.Carbohydrates are one of the main sources of energy for the human body. When consumed, they are broken down into glucose, which is used by cells for energy. Glucose is the body's preferred energy source, especially for the brain and muscles.

B.Lipids (fats) are also an important energy source, particularly for long-term energy storage, but they are not the body's primary source of energy for quick use.