Your next bonus is visual. Researchers in the Movassaghi group at MIT are studying pathways to make synthetic alkaloids. Shown in the image is one such pathway, which uses diazene-directed assembly for carbon-carbon bond formation. By letter, pair each of the reagents DMAP, NCS, and tin tetrachloride in the pathway with one of the following three possible roles: A) Electrophilic catalyst; B) Nucleophilic catalyst; C) Oxidizing agent.