Final answer:
Vitamin A is critical for numerous body functions including gene regulation, eyesight, and immune system health. Deficiency in Vitamin A can result in significant health problems such as vision issues and weakened immunity.
Step-by-step explanation:
The vitamin that plays major roles in gene regulation, eyesight, reproduction, cell differentiation, immunity, and growth is Vitamin A. This essential nutrient is critical to the development of bones, teeth, and skin, and helps maintain eyesight, enhances the immune system, is important in fetal development, and plays a role in gene expression. Vitamins are organic compounds required by the body to perform various biochemical reactions, including metabolism and the growth of bones, cells, and tissues. Vitamin A deficiency can lead to serious health issues such as impaired immunity, anemia, and visual impairments like night blindness or even total blindness.