What type of spirit is used in a Martini based on the description provided?

A Martini is traditionally known for being a classic cocktail made with either gin or vodka as its base spirit. The essence of a Martini lies in its simplicity and the way it highlights the characteristics of the chosen spirit. The most well-known variation features gin, which contributes herbal and botanical notes, while a vodka Martini offers a cleaner, more neutral profile. These two spirits align perfectly with the cocktail's requirements, making "Vodka or gin" the correct choice.

Other spirits like bourbon, whiskey, rum, or tequila do not typically fulfill the traditional requirements of a Martini, as they introduce differing flavor profiles that would alter the expected taste and experience of this iconic drink.