$O-C-=NO=C=NO-=C-N$

$($A$)$

$($B$)$

$($C$)$

Which resonance form of $OC{N}^{-}$contributes most to the real molecule?

a$)A$

b$)B$

c$)$ C

d$)$ A and $C$ same

e$)$ all same