Which vitamin refers to a group of compounds known as retinoids?

The correct answer is vitamin A, which is well-known for its role as a group of compounds called retinoids. Retinoids encompass a variety of forms, including retinol, retinaldehyde, and retinoic acid, all of which are essential for various biological functions in the body. Vitamin A is crucial for maintaining healthy vision, supporting immune function, and promoting skin health, among other roles. The body can convert carotenoids found in plant-based foods (like beta-carotene) into retinoids, further illustrating the importance of vitamin A in nutrition. This distinction as a group of compounds highlights its significant and multifaceted roles in human health.