a
The group showing electron-donating effect (such as \(-NH _{2},- OH)\) should stabilise the intermediate ions, i.e. makes the ring more reactive towards electrophilic substitution than benzene and are called activating group while electron withdrawing group (such as \(\left.-C l, N O_{2}\right)\) increases the positive charge on ring, thus deactivates the ring. Hence, phenol is more readily attacked by an electrophile