Step 1: Understanding C$_4$ pathway.
C$_4$ plants show spatial separation of initial CO$_2$ fixation and Calvin cycle to minimize photorespiration.
Step 2: Location of reactions.
C$_4$ pathway occurs in mesophyll chloroplasts.
C$_3$ pathway (Calvin cycle) occurs in bundle sheath chloroplasts.
Step 3: Conclusion.
Therefore, option (A) correctly describes the reactions in C$_4$ plants.