CAM plants keep stomata closed in daytime,thus reducing loss of water.They can do this because they

A)fix CO₂ into organic acids during the night.
B)fix CO₂ into sugars in the bundle-sheath cells.
C)fix CO₂ into pyruvate in the mesophyll cells.
D)use the enzyme phosphofructokinase, which outcompetes rubisco for CO₂.
E)use photosystem I and photosystem II at night.