What Determines Whether Rubisco Acts as an Oxygenase or a Carboxylase

Multiple Choice

What determines whether rubisco acts as an oxygenase or a carboxylase?

A) Rubisco has ten times more affinity for O₂ than for CO₂; therefore, it favors O₂ fixation.
B) If O₂ is relatively abundant, rubisco acts as a carboxylase.
C) If O₂ predominates, rubisco fixes it, and the Calvin cycle occurs.
D) Oxygenase activity is more likely at low temperatures.
E) As the ratio of CO₂ to O₂ falls in the leaf, the reaction of rubisco with O₂ is favored.