80. Which of the following statements about the Calvin cycle is true? I. Sugarcane opens stomata on days, while pineapple opens stomata at nights. II. On hot and dry days, sugarcane is more efficient to fix CO2 than rice. III. Rubisco is an enzyme involved in the first major step of carbon fixation in rice; its substrate molecules are ribulose-1,5-bisphosphate and CO2 and its product is a three-carbon compound. IV. Sugarcane and pineapple can use phosphoenolpyruvate carboxylase to capture more CO2 into a four-carbon compound in mesophyll cells. (A) I and II (B) II and III (C) III and IV (D) I, II, and III (E) I, II, III, and IV