If Cyanobacteria Never Evolved During Earth's History, How Would Their

Multiple Choice

If cyanobacteria never evolved during Earth's history, how would their absence affect the composition of Earth's atmosphere?

A) There would be less nitrogen in the atmosphere.
B) There would be less carbon in the atmosphere.
C) There would be less oxygen in the atmosphere.
D) There would be less methane in the atmosphere.
E) There would be less hydrogen in the atmosphere.