Real organs are absent in

Options

A. Mollusca
B. Coelenterata
C. Arthropoda
D. Echinodermata

Explanation

### Step-by-Step Solution:

1. **Understand the Question**: The question asks where real organs are absent among the given options: mollusca, cnidaria, arthropoda, and echinodermata.

2. **Identify the Options**:
- **Mollusca**: This group includes organisms like snails and octopuses, which have well-defined organs.
- **Cnidaria**: This group includes jellyfish and corals, which are known for having a simpler body structure.
- **Arthropoda**: This includes insects, arachnids, and crustaceans, all of which possess complex organ systems.
- **Echinodermata**: This group includes starfish and sea urchins, which also have a defined organ system.

3. **Analyze Cnidaria**:
- Cnidarians are multicellular organisms.
- They are diploblastic, meaning their body is made up of two layers of cells.
- They lack a true coelom (body cavity) and have a tissue level of organization, which means they do not have real organs.

4. **Compare with Other Groups**:
- Mollusca, arthropoda, and echinodermata all exhibit organ level organization, meaning they have specialized organs for various functions.

5. **Conclusion**: Based on the analysis, the only group that lacks real organs is **Cnidaria**. Therefore, the correct answer is option 2: **Cnidaria**.