In ${C_4}$ plants,$CO_2$ combines with

Choose the correct option for $a, b, c$ in the given diagram of the $C_4$ pathway.
$a - b - c$

In $C_4$ plants,the primary $CO_2$ fixation occurs in the chloroplasts of .......

In $C_4$ plants,the Calvin cycle occurs in

$A-$ In $C_4$ plants,carboxylation takes place in the chloroplasts of mesophyll cells and bundle sheath cells.
$R -$ In $C_3$ plants,$CO_2$ fixation occurs in mesophyll cells and bundle sheath cells.

Choose the incorrect sentence (for $C_4$ plants).