Formation of metallic copper from the sulphide ore in the commercial thermo-metallurgical process essentially involves which one of the following reactions as the major reaction?

• A
  $CuS + \frac{3}{2}O_2 \to Cu_2O + SO_2$; $Cu_2O + C \to 2Cu + CO$
• B
  $Cu_2S + \frac{3}{2}O_2 \to Cu_2O + SO_2$; $2Cu_2O + Cu_2S \to 6Cu + SO_2$
• C
  $Cu_2S + 2O_2 \to CuSO_4$; $CuSO_4 + Cu_2S \to 3Cu + 2SO_2$
• D
  $Cu_2S + \frac{3}{2}O_2 \to Cu_2O + SO_2$; $Cu_2O + CO \to 2Cu + CO_2$