32. Both C4 and CAM plants have evolved carbon dioxide-concentrating mechanisms to reduce photorespiration. The fundamental difference between these two mechanisms is:
(A) C4 involves temporal isolation, while CAM involves spatial isolation.
(B) C4 involves spatial isolation, while CAM involves temporal isolation.
(C) C4 uses PEP carboxylase, while CAM uses Rubisco as the initial carbon-fixing enzyme.
(D) C4 fixes carbon at night, while CAM fixes carbon during the day.