Which of the following vitamins serves as a coenzyme for metabolic processes?

The correct answer is the B complex vitamins, as these vitamins play a crucial role in various metabolic processes by acting as coenzymes. Coenzymes are non-protein compounds that bind to enzymes and are essential for their activity, facilitating biochemical reactions in the body.

B complex vitamins include several key vitamins such as B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), and B12 (cobalamin). Each of these vitamins has specific roles in metabolism, including the conversion of carbohydrates, fats, and proteins into energy. They are vital for processes such as DNA synthesis and repair, red blood cell formation, and the functioning of the nervous system.

In contrast, the other vitamins mentioned do not primarily function as coenzymes. Vitamin A is involved in vision, immune function, and skin health, while Vitamin D is crucial for calcium absorption and bone health. Vitamin E acts primarily as an antioxidant, protecting cells from oxidative damage. Therefore, the role of B complex vitamins as coenzymes aligns directly with their function in supporting metabolic reactions throughout the body.