Which of the following metals is NOT extracted by electrolysis?

Very reactive metals are extracted by electrolysis of their molten compounds. Aluminium (from molten aluminium oxide in cryolite), calcium and magnesium are all in this group. Their oxides cannot be reduced easily by carbon.

Iron is much less reactive. Its ore is reduced by carbon monoxide and carbon (coke) in a blast furnace. So iron is the metal not extracted by electrolysis.