Answer:
Cyanobacteria
Explanation:
Timeline of Photosynthesis on Earth
Timeline of Photosynthesis on Earth4.6 billion years ago -Earth forms
Earth forms3.4 billion years ago -First photosynthetic bacteria appear
First photosynthetic bacteria appear2.7 billion years ago- Cyanobacteria become the first oxygen producers
he first oxygen producers2.4 – 2.3 billion years ago. - Earliest evidence (from rocks) that oxygen was in the atmosphere
