External fertilisation is found in

Options

A. Reptiles
B. Birds
C. Frog
D. Earthworm

Answer

To determine which of the given options exhibits external fertilization, we can follow these steps:

### Step-by-Step Solution:

1. **Understand External Fertilization**:
- External fertilization is a reproductive process where the fertilization of the egg by the sperm occurs outside the female's body. This typically happens in an aquatic environment.

2. **Analyze the Options**:
- **Option A: Reptiles**: Most reptiles exhibit internal fertilization, where fertilization occurs inside the female's body.
- **Option B: Birds**: Birds also primarily use internal fertilization, with fertilization occurring before the egg is laid.
- **Option C: Frog**: Frogs are known to reproduce in water, where they release both eggs and sperm into the water, allowing fertilization to occur externally.
- **Option D: Earthworm**: Earthworms typically engage in a form of reproduction that involves internal fertilization, despite being in a moist environment.

3. **Identify the Correct Answer**:
- Based on the analysis, the only option that demonstrates external fertilization is **Option C: Frog**. Frogs release their gametes into the water, where fertilization occurs.

4. **Conclusion**:
- Therefore, the answer to the question "External fertilization is found in" is **C. Frog**.