What is the initial CO2 acceptor in Crassulacean Acid Metabolism (CAM) plants during the night?

A researcher compares net CO2 exchange in three plants — a C3 grass, a C4 maize, and a CAM succulent — under identical conditions: high temperature (38°C), low humidity, and CO2 at 400 ppm. Which of the following correctly predicts the relative efficiency and the key enzymatic reason?

Given below are two statements: Assertion (A) and Reason (R). Assertion (A): In CAM plants, PEP carboxylase functions as the primary CO2-fixing enzyme during the night phase. Reason (R): PEP carboxylase has a higher affinity for CO2 than RuBisCO and does not catalyse an oxygenase reaction.