Which of the following is a common additive to coffee drinks at Starbucks?

Flavor syrups are a common additive to coffee drinks at Starbucks, enhancing the taste and creating a variety of flavor profiles. These syrups are available in numerous flavors, such as vanilla, caramel, hazelnut, and seasonal options, allowing customers to customize their beverages to suit their preferences. The use of flavor syrups is a foundational part of Starbucks' menu, enabling the creation of signature drinks and seasonal specials that attract a wide customer base.

Considering the other options, while almond butter, granola, and ice cream can be found in certain menu items or in different contexts at Starbucks, they are not standard additives to coffee drinks. Almond butter might be used in non-coffee drinks or food items, granola is typically associated with breakfast or snack selections, and ice cream is primarily used in frappuccino-style beverages rather than as a standard additive to regular coffee drinks.