Which of the following is strongest Bronsted base?

$\mathrm{HClO}_4$ is the strongest acid among $\mathrm{HClO}$, $\mathrm{HClO}_2, \mathrm{HClO}_3$ and $\mathrm{HClO}_4$ as more the number of oxygen atoms attached, more is the acidity of the molecule order of acidity is : $\mathrm{HClO}$< $\mathrm{HClO}_2$ < $\mathrm{HClO}_3$ < $\mathrm{HClO}_4$ So the conjugate base order will be just the reverse: $\mathrm{ClO}^{-}$>$\mathrm{ClO}_{2}^{-}> \mathrm{ClO}$}_{3}^{-}> $\mathrm{ClO}_{4}^{-}$