A cardboard box manufacturing company is building boxes with length represented by x + 1, width by 5 − x, and height by x − 1. the volume of the box is modeled by the function below. over which interval is the volume of the box changing at the fastest average rate?


a. [1,2]


b. [1,3.5]


c. [1,5]


d. [0,3.5]