Final answer:
The Old Fashioned's premium upgrade option is to add premium whiskey, enhancing the drink's quality and flavor.
Step-by-step explanation:
The premium upgrade option for the Old Fashioned on the menu is a) Add premium whiskey. This option allows customers to enhance their drink with a higher quality or specialty whiskey, adding depth and potentially altering the flavor profile of the traditional cocktail. The Old Fashioned is a classic cocktail typically made with whiskey, sugar, water, bitters, and a citrus garnish. Upgrading the whiskey can take the drink to a new level of sophistication and taste.