Which of the following describes the importance of cyanobacteria to early earth atmosphere formation? a.) cyanobacteria released oxygen into the air, creating a protective ozone layer b.) cyanobacteria relased nitrogen into the air, creating a protective ozone layer c.) cyanobacteria absorbed excess oxygen from the air, creating proper amounts of atmospheric oxygen d.) cyanobacteria absorbed excess carbon dioxide from the air, creating a protective ozone layer