Which of the following statements is true regarding costing systems?

Select one:

a. Both absorption costing and variable costing treat all nonmanufacturing costs as period costs.

b. Under direct costing variable overhead costs only direct variable costs are considered inventoriable.

c. Some period costs are "absorbed" into a product's cost under absorption costing.

d. Under direct costing (also called variable costing) variable nonmanufacturing costs are inventoriable.