18. The payback method is criticized on the grounds that it: a. ignores obsolescence factors. b. ignores the cost of an investment c. is complicated to use d. ignores the time value of money 19. Which statement is true? a. An investment center is responsible for revenues and expenses as well as earning a return on assets. b. An investment center is only responsible for its investments c. An investment center is only responsible for revenues and expenses d. A profit center is evaluated using revenue, while an investment center is evaluated using ROl. 20. The investigation of a materials quantity variance usually begins in the: a. production department. b. purchasing department. c. sales department. d. controller's department