Question

Which of these events occurred during the Precambrian time?

Cyanobacteria filled the water and air with oxygen.

Early humans began to make tools, harvest plants, and make cave paintings.

Pangaea, the super continent, was formed.

Pangaea began to break apart into many continents separated by shallow seas.

Answer 1

Answer:I believe the answer is the first one Cyanobacteria filled the water and air with oxygen

Step-by-step explanation:

Answer 2

Cyanobacteria. The Cambrian explosion wouldn’t have happened without so much oxygen that the Cyanobacteria created