Step 1: Understanding the Concept:
Vitamins are classified as fat-soluble and water-soluble.
We need to identify the fat-soluble vitamin from the options.
Step 2: Key Formula or Approach:
No specific formula.
Need to know the classification of vitamins.
Step 3: Detailed Explanation:
Fat-soluble vitamins are A, D, E, and K.
Retinol is Vitamin A.
Ascorbic acid is Vitamin C (water-soluble).
Riboflavin is Vitamin B2 (water-soluble).
Thiamine is Vitamin B1 (water-soluble).
Thus, retinol is the fat-soluble vitamin.
Step 4: Final Answer:
Retinol is a fat-soluble vitamin.
Hence, the correct option is (B).