Which among the following pairs is not an acidic buffer?

The buffer solution is that solution which resist any change in its $\mathrm{pH}$ upon addition of small amount of acid or base to it.

Acid buffer has acidic $\mathrm{pH}$ and is prepared by mixing a weak acid and its salt with a strong base.

Here, ${\mathrm{HClO}}_4$ is a strong acid as because the chlorine atom is in its highest oxidation state.

So that's why this mixture is not a acidic buffer in nature