Identify the substance oxidised, reduced, oxidising agent and reducing agent respectively for the following reaction.

$2\mathrm{AgBr}\left(\mathrm{s}\right)+{\mathrm{C}}_6{\mathrm{H}}_6{\mathrm{O}}_2\left(\mathrm{aq}\right)⟶2\mathrm{Ag}\left(\mathrm{s}\right) +2\mathrm{HBr}\left(\mathrm{aq}\right)+{\mathrm{C}}_6{\mathrm{H}}_4{\mathrm{O}}_2\left(\mathrm{aq}\right)$

In a reaction, the substance in which oxidation state of an element increases, is oxidised, i.e. acts as reducing agent while that in which oxidation state of an element decreases, is reduced, i.e.acts as oxidising agent.