The correct increasing order of reactivity for the following molecules towards electrophilic aromatic substitution is:

Greater is the electron density on the aromatic ring, greater is the reactivity towards electrophilic aromatic substitution.The nitro and chloro group is electron-withdrawing group thus it decreases the electron density from the ring thus making it unsuitable for electrophilic substitution reaction.Whereas the methoxy group is electron-donating group and it increases electron density on benzene ring thus making it most suitable for electrophilic substitution reaction.