One of the following is unpaired in earthworm.

Options

A. Male genital pore
B. Female genital pore
C. Genital papillae
D. Spennathecae

Answer

To determine which of the following options is unpaired in earthworms, we need to analyze each option carefully:

1. **Understanding the Earthworm's Anatomy**: Earthworms are hermaphrodites, meaning they possess both male and female reproductive organs. The reproductive structures are located in segments 9 to 15.

2. **Evaluating the Options**:
- **Male Genital Pore**: This is a paired structure, with two male genital pores located in segment 18. Therefore, this option is not unpaired.
- **Female Genital Pore**: This is a single structure located in segment 14. This is a candidate for being unpaired.
- **Genital Papillae**: These are present in pairs, specifically two pairs located in segments 17 and 19. Hence, this option is also not unpaired.
- **Spermatheca**: This structure is present in four pairs, located inter-segmentally, and functions to store sperm. Therefore, this option is not unpaired either.

3. **Conclusion**: Based on the analysis, the only unpaired structure in earthworms is the **Female Genital Pore**, which is located in segment 14.

**Final Answer**: The unpaired structure in earthworms is the **Female Genital Pore**.

---