What is the main function of Vitamin A?

The main function of Vitamin A is primarily associated with maintaining healthy skin and mucous membranes. Vitamin A plays a critical role in the maintenance of epithelial tissues, which make up the outer layer of the skin and line various organs and cavities within the body. This is vital for protecting the body from pathogens and environmental damage, ensuring that tissues retain their integrity and function effectively.

While Vitamin A has other important roles, such as contributing to vision and supporting the immune system, its key function in promoting healthy skin and mucosal surfaces is widely recognized. This establishes its significance in overall health, particularly concerning cellular growth and differentiation, which are critical for maintaining the barrier function of the skin and mucous membranes.

The other options represent functions related to different vitamins or nutrients. The roles mentioned in those choices are not primarily associated with Vitamin A; for example, the "sunshine vitamin" description refers to Vitamin D, which is linked to calcium absorption, while other options pertain to vitamins or nutrients responsible for antioxidant activity or blood clotting.