The correct option is
C A→ Nitrobenzene
B→ m-bromonitrobenzene
Ist reaction is Nitration: The replacement of H atom of a benzene ring by nitro group
(NO2). It is carried out by treating benzene with conc. nitric acid and conc. sulfuric acid.
2nd reaction is bromination at p-position of nitrobenzene as this position is more electrophilic.