Which of the following are not resonance structures of each other?

• A
  $CH_3-N=C=S$ and $CH_3-S-C \equiv N$
• B
  $CH_3-C^{+}=O$ and $CH_3-C \equiv O^{+}$
• C
  $CH_3-C(=O)-OH$ and $CH_3-C(O^{-})=O^{+}-H$
• D
  $CH_2=CH-C \equiv N$ and $C^{+}H_2-CH=C=N^{-}$