Photosynthesis in $C_4$ plants is relatively less limited by atmospheric $CO_2$ levels because

Question

( A ) Rubisco in $C_4$ plants has higher affinity for $CO_2$
( B ) Four carbon acids are the primary initial $CO_2$ fixation products
( C ) Effective pumping of $CO_2 $ into bundle sheath cells
( D ) The primary fixation of $CO_2$ is mediated via PEP carboxylase