Cod liver oil is the rich source of

Options

A. vitamin A
B. calcium
C. vitamin D
D. iron

Answer

### Step-by-Step Solution:

1. **Understanding Cod Liver Oil**:
- Cod liver oil is an oil derived from the livers of cod fish, specifically the Atlantic cod or Pacific cod.

2. **Nutritional Components of Cod Liver Oil**:
- Cod liver oil is known to be rich in several important nutrients, particularly omega-3 fatty acids, vitamin A, and vitamin D.

3. **Identifying the Richest Source**:
- Among the nutrients present in cod liver oil, we need to identify which one is the most concentrated.
- While both omega-3 fatty acids and vitamins A and D are significant, vitamin D is often highlighted as being particularly abundant in cod liver oil.

4. **Health Benefits**:
- The nutrients found in cod liver oil, especially omega-3 fatty acids and vitamin D, are beneficial for various health conditions, including heart disease and arthritis.

5. **Conclusion**:
- Therefore, the answer to the question "Cod liver oil is a rich source of?" is **vitamin D**.