How is earth's early land environment different than today's land environment?

The question is asking to states on how i earth's early lang environment different than today's land environment and base on my research, I would say that in the past centuries or early ages, the Earth's land environment are compost of tree and plants and the air is still fresh. I hope you are satisfied with my answer and feel free too ask for more 

Cand d are correct because the rest are just showing your mistakes and you don’t want people who are reading a summary you wrote to see all the mistakes you made.