Arrange the given alkenes in decreasing order of their reactivity towards bromination:

The correct option is A i> ii> iii> iv
reactivity towards Bromination depends on e${}^{-}$ rich alkene since Br${}^{+}$ is electrophile.

The alkene which have more methyl group attached to the doubly bonded carbon atom will be more electron rich.

Thus the order of the reactivity towards bromination reaction can be given as follow:

$i>ii>iii>iv$
Option A is correct.