Thick-walled perennating sexual spore is

Options

A. Zygote
B. Zoospore
C. Hypnospore
D. Zygospore

Answer

To solve the question about which thick-walled perennating sexual spore is correct, we will analyze the given options step by step.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Thick-walled**: This indicates that the spore has a robust outer layer, which helps it survive in unfavorable conditions.
- **Perennating**: This refers to spores that can survive through adverse conditions, often referred to as resting spores.
- **Sexual Spore**: This is a spore formed through sexual reproduction.

2. **Analyzing the Options**:
- **Option A: Zygote**: A zygote is the fertilized egg formed by the fusion of gametes. It is not a spore, hence this option is incorrect.
- **Option B: Zoospore**: A zoospore is an asexual spore that is motile and produced during asexual reproduction. It does not fit the criteria of being a perennating sexual spore, so this option is also incorrect.
- **Option C: Hypnospore**: A hypnospore is a thick-walled spore that can survive unfavorable conditions, but it is produced asexually. Therefore, it does not meet the requirement of being a sexual spore, making this option incorrect.
- **Option D: Zygospore**: A zygospore is formed through sexual reproduction and is known for its thick wall, allowing it to survive in stressful conditions. This option fits all the criteria of being a thick-walled perennating sexual spore.

3. **Conclusion**:
- After analyzing all the options, the correct answer is **Zygospore** (Option D), as it is a thick-walled, perennating sexual spore.

### Final Answer:
The thick-walled perennating sexual spore is **Zygospore**.