Starting from a Lewis diagram of NO2− in which the left oxygen bears a single bond to nitrogen and a negative formal charge, which of the following curved-arrow descriptions correctly generates the alternative resonance contributor where the left oxygen is double-bonded to nitrogen and the negative charge resides on the right oxygen?
a) Move one lone pair from nitrogen into the N–O single bond while shifting the N=O π electrons onto the right O as a lone pair.
b) Move one lone pair from the right O into the N–O bond while pushing the N=O π electrons onto nitrogen as a lone pair.
c) Move one lone pair from the left O into the N–O bond and simultaneously shift the N=O π bond onto the right O as a lone pair.
d) Move one lone pair from the left O into the N–O bond only, leaving all other bonds and lone pairs unchanged.