Which of the following ingredients is used in the cocktail Bananas and Bourbon?

In the cocktail Bananas and Bourbon, Four Roses Bourbon is a key ingredient because it provides the foundational spirit that defines the drink’s flavor profile. Bourbon, known for its rich, sweet characteristics with notes of vanilla and caramel, complements the sweetness of bananas beautifully, creating a balanced and harmonious combination. This particular bourbon is often appreciated for its smoothness and complexity, making it an ideal choice for cocktails where the spirit should stand out while still supporting the other flavors.

While other ingredients like ginger peach syrup, orange twist, and sweet vermouth might add interesting flavors to different cocktails, they do not play a role in the classic formulation of Bananas and Bourbon. The integrity of the cocktail relies heavily on the bourbon, which is why it is the correct answer in this scenario.