Question

Unlike the atmosphere today, the atmosphere 3.5 billion years ago did not contain a. sunlight. c. gases. b. birds. d. oxygen. Please select the best answer from the choices provided A B C D

Answer 1

The correct answer for this is actually O2 or Oxygen :)

Step-by-step explanation:

I hope that answered your question in time

Answer 2

b. birds

Step-by-step explanation:

cause i think, birds where not evolved during that period of time..