Which of the following lacks respiratory pigment in Blood ?

Options

A. Earthworm
B. Cockroach
C. Rat
D. All of these

Answer

To determine which of the following lacks respiratory pigment in blood, we need to analyze the options provided: earthworm, cockroach, rat, and all of these.

### Step-by-Step Solution:

1. **Understanding Respiratory Pigments**:
- Respiratory pigments are molecules that transport oxygen in the blood. The most common respiratory pigment is hemoglobin, which is found in many organisms.

2. **Analyzing the Earthworm**:
- Earthworms possess hemoglobin as their respiratory pigment. It is dissolved in their blood plasma, allowing them to transport oxygen effectively. Therefore, earthworms do **not** lack respiratory pigments.

3. **Analyzing the Rat**:
- Rats, being mammals, also have hemoglobin in their red blood cells. This allows them to efficiently transport oxygen throughout their body. Thus, rats do **not** lack respiratory pigments.

4. **Analyzing the Cockroach**:
- Cockroaches have an open circulatory system, and they do not have hemoglobin or any other respiratory pigment in their blood. Instead, they have a fluid called hemolymph, which is colorless and does not contain red blood cells. Therefore, cockroaches **do** lack respiratory pigments.

5. **Conclusion**:
- Since both earthworms and rats have respiratory pigments, and only the cockroach lacks them, the correct answer to the question is **cockroach**.

### Final Answer:
The organism that lacks respiratory pigment in blood is **cockroach**.