Question

What is the first oxygen-producing organism?

Answer 1

Cyanobacteria

Step-by-step explanation:

Cyanobacteria or blue-green algae became the first microbes to produce oxygen by photosynthesis

Answer 2

Autotrophic Cyanobacteria.

Step-by-step explanation:

Cyanobacteria or blue-green algae became the first microbes to produce oxygen by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago.