Astral rays arise from

Options

A. centriole
B. cytoplasm
C. chromatid
D. centromere

Answer

### Step-by-Step Solution:

1. **Understanding Astral Rays**: Astral rays are structures that are formed during cell division, specifically during the mitotic phase. They play a crucial role in the organization of the spindle apparatus.

2. **Identifying the Source of Astral Rays**: Astral rays originate from the microtubule organizing center (MTOC), which is primarily the centrosome in animal cells. The centrosome contains a pair of centrioles.

3. **Role of Centrioles**: Centrioles are cylindrical structures that are part of the centrosome. They are essential for the formation of spindle fibers and astral rays during cell division.

4. **Examining the Options**:
- **Centrioles**: Present in animal cells and responsible for the formation of astral rays.
- **Cytoplasm**: While microtubules are present in the cytoplasm, they do not originate from there directly.
- **Sister Chromatids**: These are the duplicated chromosomes that are separated during cell division, not a source of astral rays.
- **Centromere**: This is the region of the chromosome where sister chromatids are joined, not related to the formation of astral rays.

5. **Conclusion**: Based on the above analysis, the correct answer is that astral rays arise from **centrioles**.

### Final Answer:
**Astral rays arise from centrioles.**