Mark the odd one out.

Options

A. Rohu
B. Sea horse
C. Jelly fish
D. Flying fish

Answer

To solve the question "Mark the odd one out," we need to analyze the given options and identify which one does not belong to the same category as the others.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are Rohu, Seahorse, Jellyfish, and Flying Fish.

2. **Classify Each Option**:
- **Rohu**: This is a type of fish known as a bonifish (bony fish). It has a skeleton made of bones.
- **Seahorse**: Also a bonifish, known scientifically as Hippocampus. It has a bony skeleton.
- **Jellyfish**: Known as Aurelia, this is not a fish but an invertebrate belonging to the phylum Cnidaria. It does not have a bony skeleton.
- **Flying Fish**: Known scientifically as Exocetus, this is also a bonifish with a bony skeleton.

3. **Determine the Odd One Out**:
- Rohu, Seahorse, and Flying Fish are all bony fish (vertebrates) with a skeleton made of bones.
- Jellyfish, on the other hand, is an invertebrate and does not belong to the fish category.

4. **Conclusion**: The odd one out is **Jellyfish** because it is not a bony fish, while the others are.

### Final Answer:
**Jellyfish** is the odd one out.

---