Salt $A$,commonly used in bakery products,on heating gets converted into another salt $B$,which itself is used for the removal of hardness of water,and a gas $C$ is evolved. The gas $C$,when passed through lime water,turns it milky. Identify $A$,$B$,and $C$.

• A
  $A = NaHCO_3, B = Na_2CO_3, C = CO_2$
• B
  $A = Na_2CO_3, B = NaHCO_3, C = CO_2$
• C
  $A = NaHCO_3, B = Na_2CO_3, C = H_2O$
• D
  $A = Na_2CO_3, B = NaOH, C = CO_2$