This question tests knowledge of organic reaction mechanisms, specifically the Friedel-Crafts alkylation reaction. A key limitation is that it fails on strongly deactivated rings like nitrobenzene, as the nitro group ($-N{O}_2$) is meta-directing and powerfully electron-withdrawing, making the ring unreactive to electrophilic substitution. The reaction in the third image shows an attempt to alkylate nitrobenzene, which will not proceed. The other reactions are valid.

Final Answer: The third reaction is not correct.