CAM Photosynthesis Improves the CO₂/H₂O Exchange Ratio Because

CAM photosynthesis improves the CO₂/H₂O exchange ratio because:

A) organic acids are decarboxylated at night.
B) organic acids are decarboxylated in daylight.
C) CO₂ capture occurs at night when the gradient for diffusion of H₂O out of the leaf is smaller.
D) CO₂ capture occurs at night when the gradient for diffusion of CO₂ into the leaf is larger.