What primary ingredient is used to make tequila?

Tequila is primarily made from the fermented juice of the blue agave plant, which is native to the region surrounding the city of Tequila in Mexico. This specific type of agave is critical for tequila production, as it contains the sugars necessary for fermentation, which are converted to alcohol during the distillation process. Blue agave has specific qualities that contribute to the distinctive flavor profile of tequila, making it the only acceptable source for genuine tequila production under Mexican law. The other options, such as sugarcane, corn, and wheat, are used in the production of other spirits like rum, whiskey, and vodka, but they do not play a role in the traditional production of tequila.