The number of resonating structures of phenoxide ion is

Resonance structures of phenoxide ion is shown below

It has non-equivalent resonance structures.

In this ion, the negative charge is non effectively delocalised.

Negative charge is delocalised between the oxygen atom and the carbon atoms.

So the total resonating structures of phenoxide anion is 5 from the above figure of resonating structures of phenoxide anion.

Hence the correct option is B) 5.