Which classic cocktail is made with whiskey and sweet vermouth?

The classic cocktail that is made with whiskey and sweet vermouth is the Manhattan. This iconic drink typically consists of a combination of rye whiskey or bourbon and sweet vermouth, often garnished with a cherry or a twist of lemon peel. The Manhattan is known for its rich, smooth flavor and is a staple in cocktail culture, representing the elegance and sophistication associated with classic mixed drinks.

While the Old Fashioned also features whiskey, it does not include vermouth and instead relies on sugar, bitters, and a twist of citrus. The Moscow Mule is a vodka-based cocktail served in a copper mug, and the Mint Julep is a refreshing cocktail made with bourbon, sugar, mint, and crushed ice, again not using sweet vermouth. This clear distinction in ingredients showcases why the Manhattan is the correct answer to the question.