Explain in brief

Dear Student, given plots are the Ellingham diagrams for Metal oxide reduction with CO. The temperature above point of intersection is the minimum temperature required for reduction of MO by C. Also, the bends in M----> MO lines indicate change of state. After one bend (melting point), M/MO is in liquid state and after second bend (boiling point), it is in gaseous state. It is only in (3) that reduction is feasible after one bend, so, the metal formed after reduction is in liquid form. So, correct answer is (3). Regards