Choose the correct option–

Options

A. Macropus - hair on skin & pinna present
B. Pleurobrachia - Cnidoblast
C. Pristis - Gitar fish
D. Scoliodon - Cat fish

Answer

To solve the question, we need to analyze each option and determine which one correctly matches the characteristics of the organisms mentioned.

### Step-by-Step Solution:

1. **Identify the Groups of Mammals**:
- Mammals are classified into three main groups based on their reproductive strategies:
- Monotremes (egg-laying mammals)
- Marsupials (pouched mammals)
- Placental mammals (those that give birth to live young).

**Hint**: Remember the three groups of mammals and their reproductive strategies.

2. **Analyze the First Option (Macropus)**:
- Macropus is a genus that includes kangaroos, which are marsupials.
- Marsupials are characterized by having hair on their skin and external ears (pinna).
- Therefore, this option is correct.

**Hint**: Look for characteristics specific to marsupials when evaluating options.

3. **Analyze the Second Option (Pleurobranchia and Nidoblast)**:
- Pleurobranchia is a genus of ctenophores (marine invertebrates).
- Nidoblast refers to a type of cell found in cnidarians, not mammals.
- This option is incorrect as it does not relate to mammals.

**Hint**: Check if the organisms mentioned belong to the same classification group.

4. **Analyze the Third Option (Pristis and Guitar Fish)**:
- Pristis refers to sawfish, which are cartilaginous fish.
- Guitar fish is a common name for Rhinobatos, which is also a type of cartilaginous fish.
- This option is incorrect as it does not involve mammals.

**Hint**: Identify if the organisms are from the mammalian class.

5. **Analyze the Fourth Option (Scoliodon and Catfish)**:
- Scoliodon is a genus of sharks, which are also cartilaginous fish.
- Catfish belong to the order Siluriformes, which is a completely different group of fish.
- This option is also incorrect as it does not relate to mammals.

**Hint**: Ensure that both organisms in the option are mammals.

6. **Conclusion**:
- After analyzing all options, the only correct option that matches the characteristics of mammals is **Option A (Macropus)**.

### Final Answer:
The correct option is **A (Macropus)**.