A respiratory pigment is absent in

Options

A. Earthworm
B. Frog
C. Rabbit
D. Cockroach.

Answer

To determine which organism lacks a respiratory pigment, we can analyze the options provided: earthworm, frog, rabbit, and cockroach.

### Step-by-Step Solution:

1. **Understanding Respiratory Pigments**:
- Respiratory pigments are molecules that carry oxygen in the blood. Common examples include hemoglobin in vertebrates and hemocyanin in some invertebrates.

2. **Analyzing the Options**:
- **Earthworm**: Earthworms have hemoglobin in their blood, which is responsible for transporting oxygen.
- **Frog**: Frogs, being amphibians, also possess hemoglobin in their blood for oxygen transport.
- **Rabbit**: Rabbits are mammals and have hemoglobin as well, which is essential for oxygen transport.
- **Cockroach**: Cockroaches are insects and do not have a respiratory pigment. Instead, they use a system of tracheae to transport oxygen directly to their tissues.

3. **Conclusion**:
- Based on the analysis, the correct answer is **cockroach**, as it is the only organism listed that does not have a respiratory pigment.

### Final Answer:
A respiratory pigment is absent in **cockroach**.