PLEASE HELP!!!! 12 POINTS!!!! :)
Before cyanobacteria appeared, Earth’s atmosphere was composed of water vapor, carbon dioxide, nitrogen and other gases. Where did these gases come from?
A. They were released by the atmosphere.
B. They were released by the biosphere.
C. They were released by the geosphere.
D. They were released by the hydrosphere.
Please explain your answer! :)