Which step is common to both the Red Bull Sour Lime Slush and the Red Bull Strawberry Slush recipes?

The correct answer highlights a shared step in the preparation of both the Red Bull Sour Lime Slush and the Red Bull Strawberry Slush, which involves pouring the final mixture into a non-alcoholic disposable cup. This step is crucial as it ensures that the beverage is served appropriately, allowing it to be transported and consumed easily by guests.

Serving drinks in disposable cups is a standard practice in many establishments, including Dave and Busters, to provide convenience for patrons. It also maintains hygiene and allows for easy cleanup after the guests have finished their drinks.

The other options involve specific actions that may only pertain to one recipe or are not relevant to the core preparation steps that define the similarities between both slush drinks. These steps may enhance the drink's presentation or flavor but do not reflect the foundational process of serving the beverage itself.