Johnson's organs are present in

Options

A. abdomen of housefly
B. head of cockroach
C. antenna of mosquito
D. none of the above

Answer

To determine where Johnson's organs are located, we can follow these steps:

### Step-by-Step Solution:

1. **Understand what Johnson's organs are**: Johnson's organs are specialized sensory structures found in certain insects. They are named after the physician Christopher Johnston.

2. **Identify the composition**: These organs are made up of sensory cells that help in detecting various stimuli.

3. **Locate the position of Johnson's organs**: Johnson's organs are specifically found in the pedicle of the antennae of insects. The pedicle is the part of the antenna that connects to the insect's head.

4. **Recognize their function**: The primary function of Johnson's organs is to detect motion, particularly in the flagellum of the antenna. This allows insects to sense their environment more effectively.

5. **Evaluate the options given**:
- **Option A**: Abdomen of housefly - Incorrect, as Johnson's organs are not located here.
- **Option B**: Head of cockroach - Incorrect, as they are not found in the head.
- **Option C**: Antenna of mosquito - Correct, as Johnson's organs are indeed located in the pedicle of the antenna.
- **Option D**: None of the above - Incorrect, since option C is correct.

6. **Conclude the answer**: Based on the information, the correct answer is **Option C: Antenna of mosquito**.