Correct reactivity order of electrophilic substitution reaction is

Electrophile attack at that position which| have higher the electron cloud +I effect and +M effect increase the electron cloud at ortho and para position of benzene ring +M effect dominate over the +I effect hence (ii) is most reactive and (i) is second most. In reactant (iii)- C1 have I effect and +M effect both hence (ii) is third most reactive and benzaldehyd have - I effect hence it is least reactive.

Hence the order of reactivity is-ii > i > iii > iv