Johnston's organ present in mosquitoes, are to detect vibration. They are present in

Options

A. Antenna
B. Appendages
C. Anal cerci
D. Mouth parts

Explanation

### Step-by-Step Solution:

1. **Identify the Organ**: The question mentions Johnston's organ, which is known for detecting vibrations in mosquitoes.

2. **Classify the Organism**: Mosquitoes belong to the class Insecta and the phylum Arthropoda. Understanding the classification helps in knowing the anatomical features of these organisms.

3. **Understand the Function of Johnston's Organ**: Johnston's organ functions as a proprioceptor, which means it helps in detecting vibrations. This is crucial for the mosquito's sensory perception.

4. **Locate the Johnston's Organ**: Johnston's organ is specifically located in the antennae of mosquitoes. This is the structure that houses these vibration-detecting receptors.

5. **Evaluate the Options**: The options given are:
- A) Antennae
- B) Appendages
- C) Anus
- D) Cerci
- E) Mouthparts

Among these, the antennae are the correct answer as they are where Johnston's organ is found.

6. **Conclusion**: The correct answer to the question is that Johnston's organ is present in the **antennae** of mosquitoes.