Final answer:
Vitamin A supplements are effective in treating night blindness, associated with an inability to see in low light due to deficiency of this vitamin. Rickets and osteomalacia are related to vitamin D deficiency, and vitamins B and C are water-soluble with distinct functions.
Step-by-step explanation:
Vitamin A supplements help treat night blindness, a condition that is characterized by the inability to see well in low light levels. This deficiency can also lead to more severe visual impairments and is especially common in developing countries. Vitamin A plays a critical role in the development of the immune system, and its deficiency can affect the body's ability to fight off infections and contribute to anemia.
Conditions like rickets and osteomalacia are caused by a deficiency in vitamin D, not vitamin A. Rickets is characterized by improper bone development in children, which arises from the malabsorption of calcium due to a lack of vitamin D, whereas osteomalacia involves the softening of bones in adults. Vitamins B and C are water-soluble vitamins with different functions; vitamin B helps maintain eyesight and vitamin C is essential for blood clotting.