Answer:
The correct answer will be option-4.1 billion years ago.
Explanation:
Earth the only planet in the universe which harbors life was formed around 4.5 billion years ago. Â
Organic molecules formed from the inorganic molecules started aggregating and formed the first single-celled organisms which were microscopic. The fossil evidence found in the deep rocks and hydrothermal vents in the ocean suggests that single-celled organisms were formed around 3.5-4.2 billion years ago.
Thus, option-4.1 billion years ago is the correct answer.
