To solve this problem, we need to understand the role of each component in the nitration of benzene.$\\$The nitration of benzene involves the generation of the nitronium ion $(NO_2^+)$, which is the active electrophile.$\\$This ion is formed by the reaction between concentrated $H_2SO_4$ and $HNO_3. \\$The reaction is as follows:$\\ H_2SO_4 + HNO_3 \rightarrow NO_2^+ + HSO_4^- + H_2O \\$In this reaction, $H_2SO_4$ acts as a catalyst and helps in the generation of $NO_2^+. \\$Now, consider the effect of adding a large amount of $KHSO_4$ to the mixture.$\\$• $KHSO_4$ is a salt that can dissociate into $K^+$ and $HSO_4^-$ ions.$\\$• The presence of additional $HSO_4^-$ ions will shift the equilibrium of the reaction towards the left,$\\$ according to Le Chatelier's principle.$\\$• This shift will reduce the concentration of $NO_2^+$ ions available for the nitration of benzene.$\\$As a result, the rate of nitration will be slower due to the decreased availability of the active electrophile.$\\$Therefore, the correct option is:$\\$Option 2: Slower