What is carbon fixation, and how does it relate to photosynthesis?

it is the absorption of co2 from the air; , and it occurs during the light-dependent reactions.
it is the reduction of co2, and it occurs during the calvin cycle.
it is the conversion of co2 into organic compounds, and it forms 3-pga.
it is the production of co2 during regeneration, and it forms rubp.