Oxidation state of $\mathrm{S}$ in ${\mathrm{H}}_2{\mathrm{SO}}_5$ and ${\mathrm{H}}_2{ \mathrm{S}}_2{\mathrm{O}}_8$ respectively are

The structure of in ${\mathrm{H}}_2{\mathrm{SO}}_5$ and ${\mathrm{H}}_2{ \mathrm{S}}_2{\mathrm{O}}_8$ can be represented with oxidation calculated from bonding electrons as,

Therefore the oxidation state for $\mathrm{S}$ in ${\mathrm{H}}_2{\mathrm{SO}}_5$ and ${\mathrm{H}}_2{ \mathrm{S}}_2{\mathrm{O}}_8$ is +6,+6.

Hence the correct option is (A).