The correct option is D CH3COOH and CH3COONa
Buffer solutions:
“The solution which resists a change in the pH value on the addition of a small amount of acid or base to it is called buffer solution”.
Note:- This does not mean that the pH will not change. All it means is that the pH change would be less which is not observable.
Buffers can be made to work around any pH value throughout the pH scale depending on the nature of buffer.
An acidic buffer solution is an aqueous solution consisting of a mixture of a weak acid and salt of its conjugate base.
HCl,HNO3,H2SO4 all are strong acids. CH3COOH is the only weak acid here.
Therefore among of all options, only in option "D", there is a pair of a weak acid and salt of its conjugate base which can show buffer activity.
Hence, Option "D" is the correct answer.