Which of the following is a nonlinear function?
A. Jeremy has 10 comic books and he buys 2 comic books every month.
B. The annual revenue of an IT firm has been decreasing by 2% per year.
C. Desmond owns a gaming store where the average number of daily customers increases by 100 each month.
D. Molly has $200 in savings. She decided to save $45 each month going forward.