Which represents the correct order of the first ionization potential of third-period elements? (AFMC 2009)

Ionization energy is the amount of energy required to remove an electron from an isolated neutral gaseous atom. Ionization energy increases from left to right in periods and it decreases down the group, but the ionization enthalpy of aluminum is less than magnesium due to loosely bond 3p electron. The correct order is Na < Al < Mg < Si .