Which of the following statements pertain to both variable costing and absorption costing?

A. The income statement discloses the amount of gross margin generated during the reporting period.

B. Fixed selling and administrative expenses are treated in the same manner as fixed manufacturing overhead.

C. Both variable and absorption costing can be used for external financial reporting.

D. Variable selling costs are written-off as expenses of the accounting period.

E. Fixed manufacturing overhead is attached to each unit produced.