Which enzyme fixes atmospheric $CO_2$ in $C_4$ plants?

$A-$ 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.

What is the primary $CO_2$ acceptor in $C_4$ plants?

Kranz anatomy is found in the leaves of .........

Identify $A, B, C$ and $D$ in the given figure and choose the correct option accordingly.

Scotoactive stomata are a characteristic of which plants?