The resonance hybrid of the nitrate ion $(NO_3^-)$ is represented as:

• A
  $O^{-1/2} \dots N \dots O^{-1/2}$ on top,with $O^{-1/2}$ at the bottom.
• B
  $O^{-2/3} \dots N \dots O^{-2/3}$ on top,with $O^{-2/3}$ at the bottom.
• C
  $O^{-2/3} \dots N^{+1} \dots O^{-2/3}$ on top,with $O^{-2/3}$ at the bottom.
• D
  $O^{-1/3} \dots N \dots O^{-1/3}$ on top,with $O^{-1/3}$ at the bottom.