Photosynthesis in `C_(4)` plants is relatively less limited by atmospheric `CO_(2)` levels because
A. Four carbon acids are the primary initial `CO_(2)` fixation products
B. the primary fixation `CO_(2)` is mediated via PEP carboxylase
C. Effective pumping of `CO_(2)` into bundle sheath cells
D. RuBisCO in `C_(4)` plants has higher affinity for `CO_(2)`