Scientists have found fossils of cyanobacteria that are more than 3.5 billion years old. How did these cyanobacteria help to change Earth’s early atmosphere to allow for the evolution of aerobic organisms? A. Cyanobacteria added oxygen to Earth’s atmosphere through the process of photosynthesis.
B. Cyanobacteria added carbon dioxide to Earth’s atmosphere through the process of cellular respiration.
C. Cyanobacteria added methane to Earth’s atmosphere through the process of chemosynthesis.
D. Cyanobacteria added hydrogen to Earth’s atmosphere through the process of nuclear fission.