$\mathrm{A} \underset{\mathrm{one} \mathrm{Eq} \mathrm{of} {\mathrm{CH}}_3\mathrm{I}}{\overset{{\mathrm{OH}}^{-}}{\to }}{\mathrm{C}}_9{\mathrm{H}}_{10}{\mathrm{O}}_3\stackrel{{\mathrm{KMnO}}_4}{\to }\underset{({{\mathrm{HCO}}_3}^{-} \mathrm{soluble})}{{\mathrm{C}}_9{\mathrm{H}}_{10}{\mathrm{O}}_4}\stackrel{\mathrm{Conc}.\mathrm{HI}/∆}{\to }3,4-\mathrm{dihydroxy} \mathrm{benzoic} \mathrm{acid}$

The substance $\mathrm{A}$ gives intense colour with ${\mathrm{FeCl}}_3$ and positive tollen's test.
The starting substrate $\mathrm{A}$ is
a)

b)

c)

d)