Which of the following is a characteristic of a shaken cocktail?

A characteristic of a shaken cocktail is that it often has a foamy texture. This foam is primarily the result of aeration that occurs when ingredients are vigorously shaken in a cocktail shaker. The shaking motion introduces air into the mixture, which helps emulsify ingredients such as juices, spirits, and egg whites, creating a frothy head on the cocktail. This texture not only enhances the visual appeal of the drink but also contributes to the mouthfeel, making for an enjoyable drinking experience.

In contrast, cocktails that are stirred typically do not have this foamy texture, as stirring is a gentler method that preserves the integrity of the ingredients without aerating them significantly. The other options do not accurately describe a primary characteristic of a shaken cocktail: while shaken cocktails can be dilutive depending on the amount of ice and time shaken, that is not a defining trait; mixers can certainly be included; and cocktails are typically served with ice, unless specifically designed to be enjoyed neat.