Step 1 :

Buffer pH value : $\"pH=pK_{a}+log\\frac{\\left$ .

Where $\"K_{a}\"$ is the strength of an acid.

Step 2 :

Here the acids are $\"HSO_{4}^{-}\"$ , $\"CH_{3}COOH\"$ and $\"HCN\"$ .

Buffer pH value = 4.30 .

For Acetic acid,

$\"4.30=4.75+log\\frac{\\left$ .

$\"4.30-4.75=log\\frac{\\left$

$\"-0.45=log\\frac{\\left$ .

For Sulfuric acid(2),

$\"4.30=1.92+log\\frac{\\left$

$\"4.30-1.92=log\\frac{\\left$

$\"3.1=log\\frac{\\left$ .

For Hydrocyanic acid,

$\"4.30=9.21+log\\frac{\\left$

$\"4.30-9.21=log\\frac{\\left$

$\"-4.91=log\\frac{\\left$ .

Conjugate acids(cations) of strong bases are ineffective bases.

If acid strength increases, then conjugate base strength decreases.

Observe the above calculations.

I will choose the combination of Sulfuric acid(2), because the ratio is greater than 1 comparing with other two combinations.