To identify the molecule that accepts CO₂ , Calvin and Benson manipulated the carbonfixation cycle by either cutting off CO₂ or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO₂ acceptor? a. The CO₂ acceptor concentration would decrease when either the CO₂ or light are cut off. b. The CO₂ acceptor concentration would increase when either the CO₂ or light are cut off. c. The CO₂ acceptor concentration would decrease when the CO₂ is cut off, but increase when the light is cut off. d. The CO 2 acceptor concentration would increase when the CO₂ is cut off, but decrease when the light is cut off.