Which vitamin is synthesised by bacteria in human gut?

Options

A. `B_(1)`
B. C
C. D
D. K

Explanation

**Step-by-Step Solution:**

1. **Identify the Vitamins Listed**: The question provides four options: Vitamin B1, Vitamin C, Vitamin D, and Vitamin K.

2. **Analyze Each Vitamin**:
- **Vitamin B1 (Thiamine)**: This vitamin is synthesized by some bacteria, protozoans, plants, and fungi, but humans cannot synthesize it.
- **Vitamin C**: This vitamin is synthesized by yeast and some plants. Humans also cannot synthesize it.
- **Vitamin D**: This vitamin is synthesized by the epidermal layer of human skin when exposed to sunlight. Therefore, it is not synthesized by gut bacteria.
- **Vitamin K**: This is a fat-soluble vitamin that is synthesized by bacteria present in the human gut. It plays a crucial role in blood clotting and preventing excessive bleeding.

3. **Conclusion**: Among the options provided, Vitamin K is the only vitamin that is synthesized by bacteria in the human gut.

4. **Final Answer**: The vitamin synthesized by bacteria in the human gut is **Vitamin K**.

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