You have a fish tank in your house, and your parents want you to clean it by emptying it out and then eventually refilling it. The volume of the tank is shown below.
V(x) = x⁷ - 10x⁶ + 40x⁵ - 96x⁴ + 176x³ - 224x² + 128x
Which of the following is a possible dimension of the volume of the tank?
a) x = 2
b) x = 3
c) x = 4
d) x = 5