What type of glass is used to serve an Old Fashioned cocktail?

The correct choice is the Lowball glass, which is traditionally used for serving an Old Fashioned cocktail. This type of glass is characterized by its short and wide design, making it ideal for drinks served with ice, particularly those that are stirred rather than shaken. The Old Fashioned is a spirit-forward cocktail typically made with whiskey (usually bourbon or rye), bitters, sugar, and a twist of citrus peel or a cherry, all of which benefit from the low profile of the Lowball glass that allows for both ease of stirring and a pleasant presentation of the drink's garnishes. The clear, wide surface area also facilitates the release of the aromas from the cocktail.

The other types of glasses mentioned do not suit the serving style of an Old Fashioned. Fiesta glasses are often used for things like margaritas, tall cooler glasses are designed for longer drinks typically containing mixers, and highball glasses are used for mixed drinks typically containing a larger ratio of mixers and are taller than lowball glasses.