If there was not an increase in cyanobacteria in early Earth, what would have happened to Earth’s early atmosphere?
A. The amount of oxygen would have increased, causing an increase in aerobic autotrophs and heterotrophs
B. The amount of oxygen would have increased, causing a decrease in aerobic autotrophs and heterotrophs.
C. The amount of oxygen would have decreased, causing an increase in aerobic autotrophs and heterotrophs.
D. The amount of oxygen would have decreased, causing a decrease in aerobic autotrophs and heterotrophs.