The order of reactivity of the given haloalkanes towards nucleophile is :

Step-by-step solution

For a given alkyl group, the order of reactivity is R - I > R - Br > R - Cl > R - F increasing bond energy decreasing halogen reactivity. This order depends on the carbon-halogen bond energy; the carbon-fluorine bond energy is maximum and thus fluorides are least reactive while carbon-iodine bond energy is minimum hence iodides are most reactive.