Replacement of Cl of chlorobenzene to give phenol requires drastic conditions. But chlorine of 2,4-dinitrochlorobenzene is readily replaced because
(a) NO2 donates e- at meta position
(b) NO2 withdraws e from ortho/para positions
(c) NO2 make ring electron rich at ortho and para
(d) NO2 withdraws e from meta position.