Final answer:
Sugar levels in dirty brown sugar drinks are determined by customer preference, drink size, and the default setting provided by the serving establishment.
Step-by-step explanation:
The sugar levels in dirty brown sugar drinks can be determined by several factors. Primarily, these factors include customer preference and the drink size. Some establishments allow customers to choose the amount of sugar they want in their drinks, which means the sweetness level is tailored to individual tastes. Conversely, the drink size can also influence sugar content, as larger drinks may contain more sugar simply due to their increased volume. However, many drinks also come with a default setting of sugar, determined by the recipe or standard serving offered by the establishment. Therefore, the correct answer would be that sugar levels are determined by customer preference, drink size, and the default setting of the drink.