Among the compounds.

The order of decreasing reactivity towards electrophilic substitution is

Benzene ring with +I group is more reactive than regular benzene followed by benzene ring with -I group.

-OCH₃ and -CH₃ are +I groups among which, -OCH₃ has high +I power than -CH₃ group.

-CCl₃ is a -I group.

Hence, the order of decreasing reactivity towards electrophilic substitution is: III > I > II > IV.