Which is the correct sequence of development in a frog?

Options

A. Egg `to` tadpole `to` frog
B. Frog `to` egg `to` tadpole
C. Tadpole `to` egg `to` frog
D. Egg `to` frog `to` tadpole

Explanation

To determine the correct sequence of development in a frog, we can break down the process into distinct stages:

1. **Egg Stage**: The female frog lays eggs in water. This is the starting point of the frog's life cycle. The eggs are fertilized externally, meaning that the male frog fertilizes the eggs after they are laid.

2. **Zygote Formation**: After fertilization, the eggs develop into zygotes. This is the single-cell stage that results from the fusion of the male and female gametes.

3. **Tadpole Stage**: The zygote undergoes several divisions and eventually hatches into a tadpole. The tadpole is a free-living larval stage that primarily lives in water and has gills for breathing.

4. **Metamorphosis**: The tadpole undergoes metamorphosis, a process that involves significant physical changes. During this stage, the tadpole develops legs (first the hind legs, then the front legs) and its tail gradually shortens as it transforms into an adult frog.

5. **Adult Frog**: Finally, after completing metamorphosis, the frog emerges as a fully developed adult frog, capable of living both in water and on land.

### Correct Sequence:
- Egg → Zygote → Tadpole → Metamorphosis → Adult Frog

### Final Answer:
The correct sequence of development in a frog is: **Egg → Tadpole → Frog.**

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