What is carbon fixation? a. the reactions that take energy from glucose, together with molecules of carbon dioxide (co2) and water (h2o), and produce atp (adenosine triphosphate) to store the sunlights energy for later use. b. the reactions that take energy from sunlight, together with molecules of carbon dioxide (co2) and water (h2o), and produce sugar molecules to store the sunlights energy for later use. c. the reactions that take energy from sunlight, together with molecules of oxygen (o2) and water (h2o), and produce sugar molecules to store the sunlights energy for later use.