What role do vitamins play in the body?

Vitamins are essential organic substances that play a critical role in various bodily processes, making option C the correct choice. They are necessary for the proper functioning of the immune system, the metabolism of food, and the synthesis of hormones and cholesterol, among other vital functions. Unlike macronutrients, such as proteins, carbohydrates, and fats that provide energy, vitamins do not serve as a primary energy source. Instead, they facilitate biochemical reactions and support overall health.

Each vitamin has specific functions, and deficiencies can lead to significant health issues. For example, vitamin C is important for collagen production and immune function, while B vitamins are essential for energy metabolism. Thus, vitamins contribute significantly to life and health, serving as coenzymes or precursors to coenzymes, which are vital for metabolic processes.

Other options suggest alternative roles that vitamins do not primarily fulfill. While vitamins can influence hormonal balances, their overarching role encompasses a broader range of biological functions, thereby highlighting their importance as the necessary organic substances for life.