Which of the following statements is most accurate?

a. The single plantwide factory overhead rate method will usually provide management with accurate product costs.

b. Activity-based costing can be used by management to determine accurate profitability for each product.

c. The multiple production department factory overhead rate method will usually result in more product cost distortion than the single plantwide factory overhead rate method.

d. Generally accepted accounting principles require activity-based costing methods for inventory valuation.