How Would Subjecting a CAM Plant at Night to Normal

How would subjecting a CAM plant at night to normal daytime temperatures affect its water use efficiency (CO₂ captured /H₂O lost) ?

A) CO₂ capture would increase, due to a temperature-induced increase in PEP carboxylase activity, which is enough to increase water use efficiency.
B) CO₂ capture would decrease due to temperature inhibition of rubisco, which would decrease water use efficiency.
C) Water use efficiency would decrease due to an increasing concentration gradient for diffusion of water out of the leaf at night.
D) Water use efficiency would increase due to more rapid diffusion of CO₂ during the day.