In coelenterates, cnidoblasts occur inside
(a) Gastrodermis
(b) Mesoglea
(c) Epidermis
(d) All the above

Options

A. Gastrodermis
B. Mesogloea
C. Epidermis
D. All the above.

Answer

To solve the question about where cnidoblasts occur in coelenterates, let's analyze each option step by step:

1. **Understanding Cnidoblasts**: Cnidoblasts, also known as cnidocytes, are specialized cells found in coelenterates (Cnidaria) that contain stinging structures called nematocysts. These cells play a crucial role in the organism's ability to capture prey and defend against predators.

2. **Option A: Gastrodermis**: The gastrodermis is the inner layer of the body wall in coelenterates that lines the gastrovascular cavity (the digestive cavity). Cnidoblasts are indeed located in the gastrodermis, as they are involved in the digestion and capturing of prey. This option is likely correct.

3. **Option B: Mesoglea**: The mesoglea is a jelly-like substance found between the epidermis and gastrodermis in coelenterates. It serves as a structural support but does not contain cnidoblasts. Therefore, this option is incorrect.

4. **Option C: Epidermis**: The epidermis is the outer layer of the body wall in coelenterates. While it does contain some types of cells, cnidoblasts are not found in the epidermis. Thus, this option is also incorrect.

5. **Option D: All the above**: Since cnidoblasts are only found in the gastrodermis and not in the mesoglea or epidermis, this option cannot be correct.

6. **Conclusion**: Based on the analysis, the only correct answer is **(a) Gastrodermis**.

### Final Answer: (a) Gastrodermis