Sexual reproduction in protists with diploid chromosomes involves

Options

A. Cyst formation
B. Zygotic meiosis
C. Gametangial meiosis
D. Binary fission.

Answer

### Step-by-Step Solution:

1. **Understanding Sexual Reproduction in Protists**:
- Sexual reproduction in protists involves the formation of gametes. These gametes are produced through a process known as meiosis, which reduces the chromosome number.

2. **Identifying the Type of Meiosis**:
- In protists with diploid chromosomes, the specific type of meiosis that occurs is called **gametangial meiosis**. This is where specialized structures (gametangia) produce gametes.

3. **Formation of Gametes**:
- During gametangial meiosis, the diploid organism undergoes meiotic division to produce haploid gametes. This is a reductional division, meaning the chromosome number is halved.

4. **Fusion of Gametes**:
- The haploid gametes then fuse during fertilization to form a diploid zygote. This zygote contains pairs of chromosomes, one from each parent.

5. **Development of the Diploid Individual**:
- The diploid zygote undergoes mitotic division (which is equational division) to develop into a diploid individual or offspring, continuing the life cycle of the organism.

6. **Clarifying Other Processes**:
- It is important to note that cyst formation does not occur during this process, and zygotic meiosis is characteristic of specific organisms like Chlamydomonas. Binary fission, on the other hand, is a method of asexual reproduction seen in organisms like Amoeba.

### Conclusion:
The correct answer to the question about sexual reproduction in protists with diploid chromosomes is **gametangial meiosis**.

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