Plants began appearing on Earth. Dinosaurs became extinct on Earth. Earth's continents became separated. Earth's moon began orbiting.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which event must have occurred before coal and oil could be formed?
Possibilities:
- Plants began appearing on Earth.
- Dinosaurs became extinct on Earth.
- Earth's continents became separated.
- Earth's moon began orbiting.

Plants began appearing on Earth.