Which option correctly defines a provitamin and gives an example relevant to vitamin A?

• A. A provitamin always refers to plant-bound minerals that require fermentation to become vitamins, so beta-carotene is a mineral precursor and liver retinol is its fermented product.
• B. A provitamin refers to a synthetic supplement designed to mimic vitamin action and is identical to the active vitamin chemically; therefore beta-carotene and retinol are chemically identical and interchangeable.
• C. A provitamin is an inactive precursor that the body converts into an active vitamin; beta-carotene in carrots is a provitamin that can be converted enzymatically to retinol (active vitamin A).
• D. A provitamin is the active, preformed form of a vitamin found in animal tissues; retinol in liver is a provitamin of beta-carotene because it transforms into carotenoids upon digestion.

Answer: (C)