Which function is Vitamin A primarily involved in?

Vitamin A plays a critical role in the development and maintenance of various tissues in the body, particularly epithelial tissues and skin. This vitamin is essential for the proper functioning of the immune system, vision, and cellular communication. Specifically, it aids in the differentiation of epithelial cells and is vital for the integrity and health of skin and mucosal surfaces. Vitamin A exists in several forms, including retinol, retinal, and retinoic acid, all of which contribute not just to skin health but also to overall tissue integrity.

While some of the other options refer to important physiological functions, they are not primarily associated with Vitamin A. For instance, growth and development are indeed influenced by Vitamin A, but this is more of a secondary role compared to its direct impact on tissue and skin development. Similarly, blood clotting is mainly governed by Vitamin K and other factors, and the growth of bones and teeth is more relevant to a range of nutrients including calcium and Vitamin D. Thus, the integral role of Vitamin A in the development of tissue and skin distinguishes it as the most accurate answer.