(B) Calcium and magnesium
Metals high in the reactivity series (K, Na, Ca, Mg, Al) are obtained by electrolytic reduction of their molten chlorides. Gold and silver occur in free state; iron is extracted by carbon reduction.
Source: Metals and Non-metals, Section 3.4.5
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The key fact from Section 3.4.5: sodium, magnesium, and calcium are obtained by electrolysis of their molten chlorides. Note that aluminium is extracted by electrolysis of aluminium oxide (not chloride), so option (C) is wrong. Iron uses carbon reduction; gold/silver occur native. Only option (B) lists two metals (Ca and Mg) correctly extracted from molten chlorides.