What is the main ingredient in a White Russian?

A White Russian is primarily made with vodka and coffee liqueur, typically Kahlúa, along with cream or milk. The vodka serves as the base spirit, while the coffee liqueur adds a rich coffee flavor that complements the smoothness of the cream. This combination creates a balanced cocktail that is both indulgent and easy to drink.

The other drink combinations provided in the question do not match the classic recipe for a White Russian. Gin and vermouth are used in a Martini, while rum and cola make a Cuba Libre, and tequila with lime juice typically refers to a Margarita. Each of these drinks has its own distinct flavors and ingredients, which differ significantly from those of a White Russian.