Which set has the two members of the same phylum?

Options

A. Cuttle fish and jelly fish
B. Tape worm and earthworm
C. Dog fish and dolphin
D. Sea mouse and sea lion

Answer

To determine which set has two members of the same phylum, we need to analyze the organisms mentioned and identify their respective phyla.

### Step-by-Step Solution:

1. **Identify the Organisms**: The question provides several pairs of organisms:
- Cuttlefish and Jellyfish
- Tapeworm and Earthworm
- Dogfish and Dolphin
- Sea Mouse and Sea Lion

2. **Determine the Phylum of Each Organism**:
- **Cuttlefish**: Belongs to the phylum **Mollusca** (specifically, the class Cephalopoda).
- **Jellyfish**: Belongs to the phylum **Cnidaria**.
- **Tapeworm**: Belongs to the phylum **Platyhelminthes**.
- **Earthworm**: Belongs to the phylum **Annelida**.
- **Dogfish**: Belongs to the phylum **Chordata** (specifically, class Chondrichthyes).
- **Dolphin**: Belongs to the phylum **Chordata** (specifically, class Mammalia).
- **Sea Mouse**: Belongs to the phylum **Annelida**.
- **Sea Lion**: Belongs to the phylum **Chordata** (specifically, class Mammalia).

3. **Compare the Phyla**:
- Cuttlefish (Mollusca) and Jellyfish (Cnidaria) - Different phyla.
- Tapeworm (Platyhelminthes) and Earthworm (Annelida) - Different phyla.
- Dogfish (Chordata) and Dolphin (Chordata) - Same phylum.
- Sea Mouse (Annelida) and Sea Lion (Chordata) - Different phyla.

4. **Conclusion**: The only pair that belongs to the same phylum is **Dogfish and Dolphin**, both of which belong to the phylum **Chordata**.

### Final Answer:
The set that has two members of the same phylum is **Dogfish and Dolphin**.