How can you prepare ${\mathrm{Cl}}_2$ from $\mathrm{HCl}$ and $\mathrm{HCl}$ from ${\mathrm{Cl}}_2?$ Write reactions only.

$\mathrm{NaCl}+\mathrm{A}⟶{\mathrm{NaNO}}_3+\mathrm{B}+{\mathrm{Cl}}_2+{\mathrm{H}}_2\mathrm{O}$
$\mathrm{B}+{\mathrm{O}}_2⟶\mathrm{C}+{\mathrm{Cl}}_2$
$\mathrm{C}+{\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}⟶\mathrm{A}$

$\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$, respectively, are:

$3{\mathrm{Br}}_2+6{{\mathrm{CO}}_3}^{2-}+3{\mathrm{H}}_2\mathrm{O}⟶5{\mathrm{Br}}^{-}+{{\mathrm{BrO}}_3}^{-}+6{{\mathrm{HCO}}_3}^{-}$

Which of the following statement says the above reaction is a disproportionation reaction?