What is commonly asked to determine the type of drink when making a Rob Roy?

When preparing a Rob Roy, determining the type of Scotch is crucial because this cocktail is essentially a whisky-based drink that relies heavily on the choice of Scotch whisky for its flavor profile. The Rob Roy is a variation of the Manhattan, traditionally made with bourbon or rye, but in this case, it substitutes Scotch, which significantly influences the drink's overall taste.

Scotch whiskies vary widely in their flavor profiles—from smoky and peaty to light and floral—so asking what kind of Scotch the customer prefers allows the bartender to tailor the drink to the patron's taste, ensuring a more personalized experience. This choice not only reflects the customer's preference but also showcases the bartender's skill in creating a balanced cocktail.

The other options, while relevant to the preparation of various cocktails, do not specifically address the unique aspect of the Rob Roy that hinges on the type of Scotch selected.