Pick the odd one out.
Frog, Crocodile, Butterfly

Explanation

To determine the odd one out from the list of Frog, Crocodile, and Butterfly based on their reproduction methods, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reproductive Methods**:
- **Frog**: Frogs typically reproduce through external fertilization. The female frog lays eggs in water, and the male frog releases sperm over the eggs to fertilize them.
- **Crocodile**: Crocodiles reproduce through internal fertilization. The male crocodile fertilizes the eggs inside the female's body, and then the female lays the fertilized eggs.
- **Butterfly**: Butterflies also reproduce through external fertilization. The female butterfly lays eggs, and fertilization occurs outside the body.
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