Electrophiles have high affinity for electrons. They attack at the site where electron-density is highest. Electron withdrawing substances increases the electron density. The electron withdrawing tendency decreases in the order : −OH>−CH3>−H>−Cl Therefore, the correct order of reactivity towards electrophile is C6H5OH>C6H5CH3>C6H6>C6H5Cl Related Theory Electrophilic substitution reaction in haloarenes occur slowly because halogen has a negative inductive effect, it decreases the electron density on the benzene ring due to resonance.