Which constitutes the correct pairing

Options

A. Flatworm-Planaria
B. Dogfish-Sea Urchin
C. Fish-Snail
D. None of the above

Explanation

To solve the question "Which constitutes the correct pairing?", we will analyze the options provided and identify the correct pairings based on biological classification.

### Step-by-Step Solution:

1. **Identify the First Pairing: Flatworm and Planaria**
- Planaria is a type of flatworm.
- Flatworms belong to the phylum **Platyhelminthes**.
- Therefore, the pairing of flatworm and Planaria is correct.

2. **Identify the Second Pairing: Dogfish and Sea Urchin**
- Dogfish is a type of fish that belongs to the phylum **Chordata**.
- Sea urchin belongs to the phylum **Echinodermata**.
- Since these two belong to different phyla, this pairing is incorrect.

3. **Identify the Third Pairing: Fish and Snail**
- Fish belong to the phylum **Chordata**.
- Snails belong to the phylum **Mollusca**.
- As these two also belong to different phyla, this pairing is incorrect.

4. **Conclusion**
- The only correct pairing from the options given is the first one: Flatworm and Planaria (Option A).
- Therefore, the answer to the question is **Option A**.

### Final Answer:
**Option A: Flatworm and Planaria is the correct pairing.**

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