RBCs do not occur in

Options

A. frog
B. cow
C. camel
D. cockroach

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which of the given animals does not have red blood cells (RBCs). RBCs, or erythrocytes, are crucial components of blood that transport gases, primarily oxygen and carbon dioxide.

2. **Identifying RBCs**: RBCs are characterized by the presence of hemoglobin, an iron-containing protein that gives blood its red color. Hemoglobin is essential for gas exchange in the body.

3. **Analyzing the Options**: We need to evaluate the options provided in the question to determine which animal does not have RBCs:
- **Camel**: This is a mammal and has RBCs, although they are nucleated.
- **Cow**: Another mammal that possesses RBCs.
- **Frog**: An amphibian that also has RBCs containing hemoglobin.
- **Cockroach**: An insect that does not have hemoglobin in its blood cells.

4. **Conclusion**: The cockroach is the only option where RBCs do not occur in the typical form. Instead, its blood is colorless because it lacks hemoglobin.

5. **Final Answer**: The correct answer is **option number 4: Cockroach**.

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