Which ingredient is added to a standard Bloody Mary mix for a spicy flavor?

The addition of horseradish to a standard Bloody Mary mix is what gives it the characteristic spicy flavor that many enjoy. Horseradish is a root vegetable known for its pungent and sharp taste, which enhances the drink's overall flavor profile. It contributes a heat that complements the tomato base and other ingredients typically found in a Bloody Mary, such as Worcestershire sauce, hot sauce, and spices.

While salt can enhance flavors, it does not provide the spiciness that many associate with a Bloody Mary. Bitters add complexity and depth of flavor but do not impart the same kind of heat as horseradish. Lime juice offers acidity and brightness, balancing the drink but lacking the specific spicy kick that horseradish delivers. This distinctive quality of horseradish is why it is the correct choice for adding spice to the mix.