An isostere is [UPSEAT 1999]

• A.        \[NO_{2}^{-}\] and \[{{O}_{3}}\]     
• B.        \[NO_{2}^{-}\] and \[PO_{4}^{3-}\]
• C.        \[C{{O}_{2}},\,{{N}_{2}}O,\,NO_{3}^{-}\]    
• D.        \[ClO_{4}^{-}\] and \[OC{{N}^{-}}\]