In the Paloma cocktail, which juice is primarily used?

The Paloma cocktail primarily uses grapefruit juice, which is essential to its identity and flavor profile. This drink, hailing from Mexico, combines grapefruit juice with tequila and often includes lime juice and soda water. The tartness and slight bitterness of grapefruit juice complement the smoothness of tequila, creating a refreshing balance that is characteristic of the Paloma. While other juices like pineapple, orange, and lemon can add their own unique flavors to various cocktails, they do not play a role in traditional Paloma recipes, making grapefruit juice the star ingredient in this specific drink.