Which of the following is NOT a way that activity based costing differs from traditional cost accounting? Select one: a. Nonmanufacturing as well as manufacturing costs may be assigned to products, but only on a cause-and-effect basis. b. Manufacturing overhead does not exist in ABC costing since costs are assigned on a cause-and-effect basis. c. Some manufacturing costs may be excluded from product costs. d. Numerous overhead cost pools are used, each of which may have it's own unique measure of activity.