A segment of chromosome breaks and rejoins after `180^(@)` rotation .
It is

Options

A. Duplication
B. Reciprocal translocation
C. Interstitial transloction
D. Inversion

Answer

To solve the question, "A segment of chromosome breaks and rejoins after 180° rotation. It is," we will analyze the options and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Chromosomal Breakage and Rejoining**:
- A chromosome can undergo structural changes when a segment breaks and reattaches. The nature of these changes can vary based on how the segment is reattached.

2. **Identifying the Type of Structural Change**:
- In this scenario, the segment of the chromosome breaks and then rotates 180° before rejoining. This specific rejoining after rotation indicates a particular type of chromosomal rearrangement.

3. **Analyzing the Options**:
- **Option A: Duplication**: This involves a segment of the chromosome being copied or duplicated. This does not involve rotation, so it is not the correct answer.
- **Option B: Reciprocal Translocation**: This is when segments from two different chromosomes break and exchange places. This is different from the scenario described, so it is also incorrect.
- **Option C: Interstitial Translocation**: This refers to the movement of a segment within the same chromosome or to another chromosome without rotation. This does not fit our scenario, making it incorrect.
- **Option D: Inversion**: This occurs when a segment of a chromosome breaks, rotates 180°, and then reattaches. This matches the description given in the question.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Inversion**. This is the process where a segment of a chromosome breaks and rejoins after a 180° rotation.

### Final Answer:
The correct answer is **Inversion**.