Evidence for aquatic ancestry of bryophytes is

Options

A. Gametophytic plant body
B. Ciliated sperms
C. Peristome teeth
D. All the above.

Answer

### Step-by-Step Solution:

1. **Understanding Bryophytes**:
- Bryophytes are non-vascular plants that include mosses, liverworts, and hornworts. They are primarily found in moist environments and have a life cycle that includes both gametophyte and sporophyte stages.

2. **Identifying Aquatic Ancestry**:
- The question asks for evidence supporting the idea that bryophytes have an aquatic ancestry. This means we need to look for characteristics that suggest they evolved from aquatic ancestors.

3. **Analyzing the Options**:
- a. **Gametophyte Plant Body**: While bryophytes have a dominant gametophyte stage, this alone does not provide direct evidence of aquatic ancestry.
- b. **Ciliated Sperms**: Bryophytes produce motile sperm (antherozoids) that are flagellated (ciliated). This characteristic is crucial for fertilization and indicates a reliance on water for reproduction, suggesting an aquatic origin.
- c. **Peristome Teeth**: These structures are involved in spore dispersal and do not provide evidence of aquatic ancestry.
- d. **All of the Above**: Since not all options support the aquatic ancestry, this cannot be the correct answer.

4. **Conclusion**:
- The most compelling evidence for the aquatic ancestry of bryophytes is the presence of ciliated sperms. Therefore, the correct answer is **b. ciliated sperms**.

### Final Answer:
**b. ciliated sperms**

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