Both D and G options. Weak base and its conjugate acid or weak acid and its conjugate base are the possible components of a buffer solution.
Explanation:
Buffer solution is the solution which gets easily dissolved in water and so called as "Aqueous solution".
Buffer solution is essentially made up of two components Known as:
i.) Weak base and its conjugate acid
ii.) Weak acid and its conjugate base
This weak acid and base solution is used to maintain the pH value of the solution in a balanced way.
When the weak acid or base solution is added to strong acid or base solution that is the way pH gets balanced .
In one word buffer solution is the solution which resists for the pH change when strong acids or bases are added.