Question

study the timeline
based on fossil evidence, about how long ago did the
first single - celled life form appear on earth?
o 130 million years ago
o 1.5 billion years ago
o 2.5 billion years ago
o 4.1 billion years ago

Explanation:

We look at the timeline. The first single - celled life form (Prokary - otic life) is marked at 4.1 BYA (billion years ago).

Answer:

4.1 billion years ago