The correct option is A CAM
CAM plants open stomata during night allowing carbon dioxide to enter the plant. Carbon dioxide fixation occurs during night. Carbon dioxide combines with PEP in presence of PEP carboxylase to form oxaloacetate. This is converted into malic acid and is stored in vacuoles during night.
During day time, the malic acid comes out of vacuoles and releases carbon dioxide which is utilised to synthesise glucose.