Which of the following is a nonlinear function?
A.
A soccer manufacturing company spends $5 on each soccer ball.
B.
The number of dogs in a town increases by 20 per neighborhood per year.
C.
The items at a clothing store are sold at a discount of 20% off the original price.
D.
The number of students enrolling at a high school increases each year by a factor of 1.25.