The compound ‘C’ in the reaction is

-NH2 group is a highly activating group. Direct bromination leads to trisubstitution to form a white precipitate of 2,4,6 - tribromo phenol;To decrease the activating power,aniline is subjected to acetylation;-NH2 converts to -NHCOCH3 , the lone pair of nitrogen now is not only delocalized on benzene ring but also on -COCH3;Electron density on benzene ring of acetanilide decreases as compared to aniline;-NHCOCH3 is moderately activating group towards ESR;Thus mono bromination occurs,para product is the major product;Ortho product due to steric hindrance is the minor product;Para bromo acetanilide on acidification gives give para bromo aniline;