The enzyme ribulose bisphosphate carboxylase (Rubisco) normally adds carbon dioxide to ribulose 1,5-bisphosphate. However, it will also catalyze a competing reaction in which O₂ is added to ribulose 1,5-bisphosphate to form 3-phosphoglycerate and phosphoglycolate. Assume that phosphoglycolate is a compound that cannot be used in any further reactions. If O₂ and CO₂ have the same affinity for Rubisco, which of the following is the lowest ratio of CO₂ to O₂ at which a net synthesis of sugar can occur?

(a) 1:3

(b) 1:2

(c) 3:1

(d) 2:1

This is not a multiple choice question. Pick one ratio and explain it and your reasoning in the answer box below