Which ingredient determines the sweetness of the Trenta Teavana Shaken Iced Peach Green Tea?

The ingredient that determines the sweetness of the Trenta Teavana Shaken Iced Peach Green Tea is peach syrup. This syrup is specifically added to enhance the flavor profile of the drink, contributing a significant amount of sweetness that balances the natural bitterness of the green tea. The peach syrup not only serves to sweeten the beverage but also infuses it with a fruity peach flavor that is central to this drink's identity.

The other components, such as green tea, water, and lemonade, play roles in the beverage's overall flavor and texture, but they do not provide the primary sweetness. Green tea imparts a refreshing taste, water acts as a diluent, and while lemonade adds a citrusy twist, it isn't primarily responsible for the sweetness in the drink. The sweetness specifically comes from the addition of the peach syrup.