Which fat-soluble vitamin is important for vision, bone health, and immune system function?

Vitamin A is essential for several key functions in the body, including vision, bone health, and immune system function. This vitamin plays a critical role in maintaining good eyesight, particularly in low-light conditions, by contributing to the production of rhodopsin, a pigment in the retina that is necessary for night vision.

Additionally, Vitamin A is involved in the regulation of bone health. It helps maintain the health of bones by supporting the activity of osteoclasts, which are cells that break down bone, and it also contributes to the formation of new bone cells.

Moreover, Vitamin A supports the immune system by assisting in the development and differentiation of immune cells. This can enhance the body’s ability to fight off infections and maintain overall health.

The other vitamins listed have their own significant roles but do not collectively encompass the three functions highlighted in the question. For instance, Vitamin K is primarily involved in blood clotting, while Vitamin D is crucial for calcium absorption and bone metabolism. Vitamin B6 primarily supports protein metabolism and neurotransmitter synthesis. Therefore, Vitamin A is the most appropriate answer as it addresses all three functions mentioned.