Precursor of Vitamin D is :

Question

Accepted Answer

Option 4, 7-dehydrocholesterol, is the correct answer as the precursor of Vitamin D. Here's a detailed explanation:

1. **Why Option 4 is Correct:**
   - 7-dehydrocholesterol is a compound found in the skin of humans and many animals. When the skin is exposed to ultraviolet B (UVB) rays from sunlight, 7-dehydrocholesterol undergoes a chemical reaction to form cholecalciferol, also known as Vitamin D3. This process is the primary natural source of Vitamin D for humans. Therefore, 7-dehydrocholesterol is rightly identified as the precursor of Vitamin D.

2. **Why the Other Options are Incorrect:**
   - **Option 1: Cholesterol**
     - While cholesterol is a vital substance in the body and is involved in the synthesis of various hormones and vitamin D, it is not the direct precursor of Vitamin D. The specific precursor is 7-dehydrocholesterol, which is a derivative of cholesterol.
   
   - **Option 2: Retinol**
     - Retinol is a form of Vitamin A, not Vitamin D. It plays a crucial role in vision, immune function, and skin health. It is not involved in the synthesis of Vitamin D, making it an incorrect choice for this question.
   
   - **Option 3: Calcium**
     - Calcium is a mineral essential for bone health and various bodily functions, but it is not a precursor to Vitamin D. In fact, Vitamin D helps in the absorption of calcium in the body. Therefore, calcium is not related to the synthesis of Vitamin D and is not the correct answer.

In conclusion, 7-dehydrocholesterol is the specific precursor that, upon exposure to sunlight, leads to the production of Vitamin D in the body, making Option 4 the correct answer.