What is the middle line of the shaker filled with when making a Grande teavana shaken iced blackberry mojito tea?

In preparing a Grande Teavana Shaken Iced Blackberry Mojito Tea, the middle line of the shaker is filled with water. This step is crucial as it helps to dilute the syrup and the tea, creating a balanced flavor profile. Water is necessary to ensure the drink is refreshing and not overly sweet, giving it a lighter and more enjoyable taste.

The recipe aims to achieve a harmonious blend of flavors, and without the water, the drink could be too concentrated. The other options, while important in the recipe, are not suited for filling the middle line. For instance, blackberry syrup is used to add sweetness and flavor, lemonade is used for a citrusy kick, and ice is essential for chilling the drink but does not fill the specified line in the shaker. Thus, using water is the correct action to achieve the intended taste and consistency for this beverage.