Why are iron oxides in rocks evidence for prehistoric photosynthesis? (1 point)
o Iron oxides form when carbon dioxide, a reactant of photosynthesis, is in the atmosphere.
o Iron oxides form when cyanobacteria use carbon dioxide for photosynthesis.
o Iron oxides form when cyanobacteria produce oxygen via photosynthesis.
o Iron oxides form when oxygen, a product of photosynthesis, is in the atmosphere.
