What role do vitamins play in the body?

Vitamins play a crucial role in regulating various bodily processes, which is why the selected answer is correct. They are organic compounds that are essential for numerous biochemical functions in the body. For instance, certain vitamins act as coenzymes or precursors for enzyme systems that facilitate metabolic reactions, helping with energy production, immune function, and the maintenance of healthy skin and vision. By regulating these processes, vitamins ensure that the body operates efficiently and maintains overall health.

The other options do not accurately reflect the role of vitamins. While vitamins do not provide direct energy, they are vital in helping the body utilize energy from macronutrients. They are indeed essential for many bodily functions, contrary to the implication that they are not necessary. Additionally, while some vitamins may assist in digestion indirectly, their functions extend well beyond that, influencing metabolism, growth, and cellular repair. Therefore, the statement that they only assist in digestion is overly simplistic and doesn't capture the full spectrum of their importance.