Multiple choice

When did life forms first exist on Earth?

  1. 4.5 billion years ago

  2. 3.8 billion years ago

  3. 250 million years ago

  4. 2 million years ago

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Evidence for the earliest life forms, such as stromatolites, dates back to approximately 3.8 billion years ago.