Assertion :- Colchicing induces polyploidy
Reason : Colchicine causes disjucation of chromosomes.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion, then mark (1)
B. If both Assertion and Reason are true ,but the Reason is not the correct explanation of the Assertion, then mark (2).
C. If Assertion is true, but Reason is false , then mark (3)
D. If both Assertion and Reason are false. , then mark (4)

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Colchicine induces polyploidy."
- Polyploidy refers to the condition where an organism has more than two complete sets of chromosomes. Colchicine is known to induce polyploidy by interfering with the normal process of cell division.

2. **Understanding the Reason**:
- The reason provided is that "Colchicine causes disjunction of chromosomes."
- Disjunction refers to the separation of chromosomes during cell division. However, colchicine does not cause disjunction; instead, it inhibits the proper segregation of chromosomes.

3. **Mechanism of Action of Colchicine**:
- Colchicine works by interfering with the spindle fibers that are responsible for separating chromosomes during cell division.
- By disrupting the spindle fiber organization, colchicine prevents the chromosomes from segregating properly, leading to an increase in the number of chromosome sets in the resulting cells, hence inducing polyploidy.

4. **Evaluating the Truth of Assertion and Reason**:
- The assertion is true because colchicine does induce polyploidy.
- The reason is false because colchicine does not cause disjunction; it inhibits the segregation of chromosomes.

5. **Conclusion**:
- Therefore, the correct evaluation is that the assertion is true, but the reason is false.

### Final Answer:
- Assertion is true, but the reason is false.