What is the primary alcohol base used in a Mimosa?

The primary alcohol base used in a Mimosa is typically Champagne. A Mimosa is a classic cocktail made by combining equal parts of chilled Champagne and orange juice. This sparkling wine is preferred because it has the right balance of acidity, effervescence, and flavor that complements the sweetness of the orange juice, creating a refreshing and light beverage.

While Prosecco (the answer provided) can also be used as a variation in Mimosas, traditional recipes call for Champagne. Other spirits like vodka and whiskey do not form part of a Mimosa's standard recipe and would change the character of the drink significantly, as they do not have the same qualities as sparkling wines.