The electrolytes usually used in the electroplating of gold and silver, respectively, are:

For a smooth and uniform electroplating, the electrolyte must give a very low but steady concentration of free metal ions at the cathode. This is best achieved when the metal to be plated is present in the bath as a stable complex ion. Cyanide ligands are specially suited for this purpose because they form highly stable complexes with many noble metals, keeping the concentration of the free metal ion extremely small and thereby allowing slow, even deposition.

We have that gold(I) forms the complex

$$[Au(CN)_2]^-$$

by reacting with two cyanide ions. The salt most commonly employed is potassium dicyanoaurate(I), $$K[Au(CN)_2]$$. In aqueous solution it furnishes the anion $$[Au(CN)_2]^-$$, which therefore serves as the gold-containing species in the electroplating bath.

In the same manner, silver(I) combines with two cyanide ions to give the complex

$$[Ag(CN)_2]^-,$$

and the electrolyte actually used industrially is potassium dicyanoargentate(I), $$K[Ag(CN)_2]$$. On dissolving, this salt supplies the same complex anion $$[Ag(CN)_2]^-$$ that maintains a low concentration of free $$Ag^+$$ during plating.

Thus, for both metals the preferred electrolytes are the respective dicyanide complexes:

$$\text{Gold bath:}\; [Au(CN)_2]^-$$

$$\text{Silver bath:}\; [Ag(CN)_2]^-$$

Looking at the given options, only Option D lists $$[Au(CN)_2]^-$$ for gold and $$[Ag(CN)_2]^-$$ for silver.

Hence, the correct answer is Option D.