The chemicals and the reaction conditions required for the preparation of ethane are:

• A
  $C_2H_5I, Zn-Cu, C_2H_5OH$
• B
  $CH_3Cl, Na, \text{dry ether}$
• C
  $KOOC-CH=CH-COOK, \text{electrolysis}$
• D
  $CH_3CO_2Na, NaOH, CaO, \Delta$