Similarity in Ascaris lumbricoides and Anopheles stephensi is
(a) Sexual dimorphism
(b) Metamerism
(c) Anaerobic respiration
(d) Endoparastitism

Options

A. Sexual dimorphism
B. Metamerism
C. Anaerobic respiration
D. Endoparastitism

Answer

To determine the similarity between Ascaris lumbricoides (a parasitic roundworm) and Anopheles stephensi (a mosquito), we will analyze the given options one by one.

### Step-by-Step Solution:

1. **Understanding the Organisms**:
- Ascaris lumbricoides is a parasitic roundworm that lives in the intestines of its host.
- Anopheles stephensi is a species of mosquito known for being a vector for malaria.

2. **Analyzing the Options**:
- **Option (a) Sexual dimorphism**: This refers to the differences in form between male and female members of the same species. Both Ascaris lumbricoides and Anopheles stephensi exhibit sexual dimorphism, as males and females can be morphologically distinguished.
- **Option (b) Metamerism**: This refers to the segmentation of the body into repeated units. Ascaris does not exhibit metamerism, and Anopheles, being an insect, does not show true metamerism in the same way as segmented worms do.
- **Option (c) Anaerobic respiration**: This is a type of respiration that does not use oxygen. While some organisms can perform anaerobic respiration, it is not a shared characteristic between Ascaris and Anopheles.
- **Option (d) Endoparasitism**: Ascaris is an endoparasite, but Anopheles is not; it is an external organism that feeds on blood.

3. **Conclusion**:
- The only option that correctly identifies a similarity between Ascaris lumbricoides and Anopheles stephensi is **(a) Sexual dimorphism**. Both organisms have distinct male and female forms.

### Final Answer:
The similarity in Ascaris lumbricoides and Anopheles stephensi is (a) Sexual dimorphism.

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