Which statement about carbohydrates is true?

• A. They are a large group of organic compounds including sugars, starch, and cellulose, and can be broken down to release energy.
• B. They are nitrogen-rich compounds essential for muscle growth.
• C. They are inorganic minerals with crystal structure.
• D. They are a type of fat that stores energy.

Answer: (A)

Carbohydrates are a broad family of organic compounds that includes simple sugars, complex carbohydrates like starch, and structural forms like cellulose. They are metabolized to release energy, making them the body's main quick-energy source. The energy yield from carbohydrate metabolism is about 4 kilocalories per gram. This description captures both the variety of carbohydrate types and their primary role in supplying energy, which is why this statement is correct. In contrast, proteins are nitrogen-containing molecules primarily used for growth and repair, minerals are inorganic essentials with specific crystalline structures, and fats are lipids that store energy differently.