Type of sexual reproduction in protists, bearing diploid chromosome is :

Options

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

Answer

To solve the question regarding the type of sexual reproduction in protists that bear diploid chromosomes, we can analyze the given options step by step.

### Step-by-Step Solution:

1. **Understanding the Question**:
The question asks for the type of sexual reproduction in protists that involves diploid chromosomes. Diploid means that the organism has two sets of chromosomes, one from each parent.

2. **Analyzing the Options**:
- **Option 1: Zygotic Meiosis**:
- Zygotic meiosis occurs after karyogamy, which is the fusion of two nuclei. This process results in a diploid zygote that undergoes meiosis to produce haploid spores. Therefore, this option is not correct as it does not represent a type of sexual reproduction that maintains diploid chromosomes.

- **Option 2: Binary Fission**:
- Binary fission is an asexual reproduction method where a single organism divides into two identical organisms. This option is incorrect since it does not involve sexual reproduction.

- **Option 3: Cyst Formation**:
- Cyst formation refers to a dormant stage that some protists enter under unfavorable conditions. This process is not a type of sexual reproduction, making this option incorrect.

- **Option 4: Gametangial Meiosis**:
- Gametangial meiosis is a type of sexual reproduction in which specialized structures called gametangia produce gametes. In this process, the diploid organism undergoes meiosis to form haploid gametes that can fuse to form a diploid zygote. This option is correct as it involves the production of diploid chromosomes during the initial stages.

3. **Conclusion**:
The correct answer is **Gametangial Meiosis**, as it is the type of sexual reproduction in protists that involves diploid chromosomes.

### Final Answer:
**Gametangial Meiosis**