Answer:
C. The total price depends on the number of boxes.
Explanation:
In a graph, the x-variable is the independent variable; it is what you can change.
The y-variable is the dependent variable; its value depends on the value of the x-variable.
In this case, the y-variable is the total price of cupcakes, which depends on the x-variable, the number of boxes. C is your answer.
Hope this helps!