One of the functions of retinol as a form of Vitamin A is:

Retinol, a form of Vitamin A, plays a vital role in night vision improvement due to its involvement in the formation of rhodopsin, which is a pigment found in the retina that allows the eyes to adapt to low-light conditions. When light hits rhodopsin, it triggers a biochemical process that converts light signals into electrical signals sent to the brain, enabling vision in dim lighting. This specific function highlights the importance of retinol in maintaining healthy vision, especially in low-light environments.

Other options may represent functions associated with Vitamin A but aren’t as directly connected to retinol as night vision. For example, while Vitamin A can have antioxidant properties, that role is primarily attributed to other compounds within the Vitamin A family, like carotenoids. Similarly, while there are links between Vitamin A and immune function, the improvement of night vision remains one of the most critical and specific roles associated with retinol, distinguishing it as the correct answer in this context.