Give reasons why the presence of a nitro group at o/p increases the reactivity of haloarenes towards nucleophilic substitution reactions.
a. The nitro group is a strong electron-withdrawing group.
b. The nitro group enhances the resonance stabilization of the haloarene.
c. The nitro group facilitates the release of electrons.
d. The nitro group increases the steric hindrance in the haloarene.
