Benzene reacts with ${\mathrm{H}}_2{\mathrm{SO}}_4$ only when the acid is

 Typically, fuming sulphuric acid is used to sulphonate benzene at room temperature. We must use hot, concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ because sulphonation occurs in concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ but more slowly. 

Therefore, the correct option is (D) Mixed with ${\mathrm{HNO}}_3$.