Function of vitamin K is

Options

A. Respiration
B. Carbonydrate metablism
C. Regulation of calcium and phosphate metabolism
D. Blood clotting

Answer

### Step-by-Step Solution:

1. **Understanding Vitamin K**: Vitamin K is a fat-soluble vitamin that plays a crucial role in various bodily functions.

2. **Identifying Functions**: The question asks about the functions of vitamin K. We need to analyze the options provided:
- a. Respiration
- b. Carbohydrate metabolism
- c. Regulation of calcium and phosphorus metabolism
- d. Blood clotting

3. **Analyzing Each Option**:
- **Option a (Respiration)**: Vitamin K is not directly involved in the respiration process.
- **Option b (Carbohydrate metabolism)**: Vitamin K does not play a significant role in carbohydrate metabolism.
- **Option c (Regulation of calcium and phosphorus metabolism)**: While vitamin K does have some influence on calcium metabolism, it is not its primary function.
- **Option d (Blood clotting)**: Vitamin K is essential for the synthesis of certain proteins that are required for blood clotting.

4. **Conclusion**: Based on the analysis, the primary function of vitamin K is related to blood clotting. It acts as a coenzyme for vitamin K-dependent carboxylase, which is necessary for the synthesis of proteins that facilitate blood coagulation.

5. **Final Answer**: Therefore, the correct answer is **option D: Blood clotting**.