On heating ammonium dichromate and barium azide separately,we get:

• A
  $N_2$ in both cases
• B
  $N_2$ with ammonium dichromate and $NO$ with barium azide
• C
  $N_2O$ with ammonium dichromate and $N_2$ with barium azide
• D
  $N_2O$ with ammonium dichromate and $NO_2$ with barium azide