Vitamin A, also known as retinol, is a fat-soluble vitamin that is necessary for normal vision, growth, and development. Let`s examine each option to understand why retinol is the correct answer.

Option 1: Ascorbic acid is actually another name for vitamin C, not vitamin A. Vitamin C is necessary for the growth, development, and repair of body tissues.

Option 2: Retinol is indeed another name for vitamin A. This vitamin is essential for maintaining healthy skin and mucous membranes, promoting good vision, and supporting the immune system.

Option 3: Thiamine, also known as vitamin B1, is not the same as vitamin A. Vitamin B1 is important for converting food into energy and maintaining proper heart and nerve function.

Option 4: Riboflavin, also known as vitamin B2, is not the correct answer either. Vitamin B2 is involved in various metabolic processes, including the breakdown of carbohydrates, fats, and proteins.

Therefore, option 2, retinol, is the correct answer for the alternative name of vitamin A.