Cell-tissue organisation occurs in

Options

A. Amoeba
B. Hydra
C. Tapeworm
D. Ascaris.

Answer

To answer the question "Cell-tissue organization occurs in which of the following phylum?", we can follow these steps:

### Step 1: Understand the Levels of Organization
- Organisms can be classified based on their level of organization. The levels include cellular, tissue, organ, and organ system levels.

### Step 2: Analyze the Phylum Options
- **Phylum Porifera**: Organisms in this phylum, like sponges, exhibit a cellular level of organization. They do not have true tissues; instead, they have a loose aggregation of cells.
- **Phylum Cnidaria**: This phylum includes organisms such as hydra and jellyfish. They have a tissue level of organization, where similar cells are grouped together to perform specific functions.
- **Phylum Platyhelminthes**: Organisms like tapeworms belong to this phylum, which shows an organ level of organization, indicating that tissues are organized into organs.
- **Phylum Aschelminthes (Nematoda)**: Ascaris is an example here, which also demonstrates an organ system level of organization.

### Step 3: Identify the Correct Answer
- Since the question specifically asks about cell-tissue organization, the correct answer is **Cnidaria** (specifically hydra), as it is the only phylum listed that exhibits a tissue level of organization.

### Conclusion
- Therefore, the answer to the question is **Cnidaria**.

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