Which vitamin is crucial for maintaining healthy vision?

Vitamin A plays a vital role in maintaining healthy vision, making it the correct response to this question. This vitamin is essential for the production of rhodopsin, a protein in the retina that is crucial for vision in low-light conditions. Additionally, Vitamin A helps maintain the health of the cornea, the outer covering of the eye, and contributes to overall eye health. Deficiency in Vitamin A can lead to severe eye problems, including night blindness and more serious conditions like xerophthalmia, which can result in blindness if left untreated.

The other vitamins listed, while important for various body functions, do not have the same direct impact on vision. Vitamin K is primarily involved in blood clotting, Vitamin B12 is essential for nerve function and red blood cell formation, and Vitamin D is important for bone health and immune function. Thus, while they contribute to overall health, they do not specifically support eye health in the way that Vitamin A does.