Why are iron oxides in rocks evidence for prehistoric photosynthesis?(1 point)

Responses

Iron oxides form when cyanobacteria use carbon dioxide for photosynthesis.
Iron oxides form when cyanobacteria use carbon dioxide for photosynthesis.

Iron oxides form when carbon dioxide, a reactant of photosynthesis, is in the atmosphere.
Iron oxides form when carbon dioxide, a reactant of photosynthesis, is in the atmosphere.

Iron oxides form when cyanobacteria produce oxygen via photosynthesis.
Iron oxides form when cyanobacteria produce oxygen via photosynthesis.

Iron oxides form when oxygen, a product of photosynthesis, is in the atmosphere.

1 answer

Iron oxides in rocks are evidence for prehistoric photosynthesis because iron oxides form when cyanobacteria produce oxygen via photosynthesis. This suggests that there was an increase in oxygen in the atmosphere due to the activity of cyanobacteria, indicating that photosynthesis was occurring.