The reaction in option (i) is an example of Finklestein reaction, which is a halogen exchange reaction, where alkyl iodide is produced by treating alkyl halides with NaI in dry acetone. The reaction in option (ii) is an addition reaction, where an alkene is converted to corresponding alkyl halide. The reaction in option (iii) is a substitution, and the reaction in (iv) is an electrophilic substitution. Hence option (i) is correct.