Mitotic poison is

Options

A. Nitrate
B. Carbon dioxide
C. Colchicine
D. Trehlose.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about mitotic poisons, which are substances that interfere with the process of mitosis (cell division).

2. **Identifying the Options**: The options provided are nitrate, carbon dioxide, colchicine, and trehalose.

3. **Analyzing Each Option**:
- **Nitrate**: While it can be toxic in large amounts, it does not specifically inhibit mitosis.
- **Carbon Dioxide**: Similar to nitrate, it can be harmful in high concentrations but is not classified as a mitotic poison.
- **Colchicine**: This is an alkaloid derived from the autumn crocus. It is known to inhibit microtubule polymerization by binding to tubulin, which is crucial for the formation of the mitotic spindle during cell division.
- **Trehalose**: This is a sugar and does not have any known effects on mitosis.

4. **Conclusion**: Based on the analysis, colchicine is the only substance among the options that acts as a mitotic poison by disrupting the process of mitosis.

5. **Final Answer**: The correct option is **colchicine**.