Nitration is an example of aromatic electrophilic substitution reaction and its rate depends upon the group already present in the benzene ring. Out of benzene and phenol,which one is more easily nitrated?

(B) Phenol is more easily nitrated because of the presence of the $-OH$ group. The $-OH$ group increases the electron density on the benzene ring due to its $+M$ (mesomeric) effect. Consequently,the electrophile,nitronium ion $(NO_2^+)$,attacks the phenol ring much more readily than the benzene ring.