Which one of the following vitamins can be synthesised by humans ?

Options

A. Niacin
B. Pantothenic acid
C. Folic acid
D. Ascorbic acid

Answer

**Step-by-Step Solution:**

1. **Identify the Vitamins Listed**: The question provides four options: niacin, pantothenic acid, folic acid, and ascorbic acid.

2. **Understand the Synthesis of Vitamins**: We need to determine which of these vitamins can be synthesized by the human body.

3. **Analyze Each Option**:
- **Niacin (Vitamin B3)**: Niacin can be synthesized by the human body from the amino acid tryptophan. It is a water-soluble vitamin and acts as a coenzyme in carbohydrate metabolism.
- **Pantothenic Acid (Vitamin B5)**: This vitamin is essential for synthesizing coenzyme A but cannot be synthesized in sufficient quantities by the human body.
- **Folic Acid (Vitamin B9)**: Folic acid is crucial for DNA synthesis and cell division but must be obtained through diet as it cannot be synthesized in adequate amounts by humans.
- **Ascorbic Acid (Vitamin C)**: This vitamin is important for the health of bones, connective tissues, and muscles, but humans cannot synthesize it and must obtain it from dietary sources.

4. **Conclusion**: After analyzing all the options, we find that niacin is the only vitamin that can be synthesized by humans.

5. **Final Answer**: The correct answer is **niacin**.

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