In the reaction, the intermediate(s) is (are)

- $\mathrm{OH}$ and in aqueous in alkaline medium $-\overline{\mathrm{O}}$ are ortho and para directing. We expect the main intermediate products as mono ortho/para substituted product. Remember! if we consider (b), which could be there in small amount then we need to consider even (d) because $-\overline{\mathrm{O}}$ is strongest activating group that facilitates electrophilic substitution reaction overall on the ring. $-\overline{\mathrm{O}}$ activates ortho and para position more but doesn't deactivate the meta position. We get a small amount of even the meta substituted product. But, as the question appears to be directly concerned answer should be only (a) and (c). Reaction mechanism (Electrophilic substitution) Conceptual II