The correct option is D 0.1M CH3COONa
In option(a), NH4OH is a weak base, NH4Cl is a salt of its conjugate acid. Thus, this is a basic buffer.
In option(b), H2CO3 is a weak acid and NaHCO3 is a salt of its conjugate base. This is an acidic buffer.
In option (c), the salt is formed by a weak acid and a weak base. So, it acts like a buffer too.
In option(d),
CH3COONa is the salt of a strong base sodium hydroxide NaOH and a weak acid acetic acid CH3COOH.
All buffers are not affected by dilution but in the case of the salt, pH would change.
You can also reason this out by looking at the underlying equations, concentration plays a role only in the pH equation of a salt, whereas in buffer solutions, the ratio of concentrations of salt and base/acid are involved, eliminating the volume factor.