Which one of the following is the correct order of reactivity of Mg, Al, Zn and Fe with HCl?

In the reactivity series (activity series) of metals, the order from most reactive to least reactive among these is: Mg > Al > Zn > Fe. This is consistent with their standard reduction potentials — magnesium is the most reactive and reacts vigorously with dilute HCl to release H2, followed by aluminium, then zinc, then iron. Hence the correct order is Mg > Al > Zn > Fe.