In the solar system, earth was supposed to have been formed about

Options

A. 200 bya
B. 4.5 mya
C. 4.5 bya
D. 400 mya

Explanation

**Step-by-Step Solution:**

1. **Understanding the Formation of Earth**: The question asks about the time of Earth's formation in the solar system. It is important to know the approximate age of Earth in relation to the formation of the solar system.

2. **Identifying the Time Frame**: According to scientific estimates, Earth is believed to have formed around 4.5 to 5 billion years ago. This time frame is based on various geological and astronomical evidence.

3. **Clarifying the Primitive Conditions**: At the time of Earth's formation, the environment was very different from today. It was a reducing atmosphere, meaning that it lacked free oxygen and was composed of other gases.

4. **Comparing with Other Time Periods**: The transcript mentions other significant events in Earth's history:
- Dinosaurs appeared around 200 million years ago.
- Australopithecus, an early human ancestor, existed around 4.5 million years ago.
- The Mesozoic era, known for dinosaurs, occurred around 400 million years ago.

5. **Conclusion**: Based on the information provided, the correct answer to the question about when Earth was formed in the solar system is approximately 4.5 to 5 billion years ago.

**Final Answer**: Earth was formed about 4.5 to 5 billion years ago.

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