1. Which of the following nutrients is essential for energy metabolism in the body? A. Vitamin C B. Calcium C. Vitamin B12 D. Iron Correct answer: C. Vitamin B12 Rationale: Vitamin B12 is essential for the production of red blood cells and the metabolism of carbohydrates and fats for energy. 2. What is the main function of carbohydrates in the body? A. Provide energy B. Build and repair tissues C. Support immune function D. Aid in digestion Correct answer: A. Provide energy Rationale: Carbohydrates are the body's main source of energy, providing fuel for physical activity and essential bodily functions. 3. Which of the following minerals is important for maintaining fluid balance in the body? A. Iron B. Magnesium C. Potassium D. Zinc Correct answer: C. Potassium Rationale: Potassium is an electrolyte that plays a key role in fluid balance, muscle function, and nerve transmission. 4. What is the recommended daily intake of water for an average adult? A. 4 cups