At the end of the accounting period, Armstrong Corporation reports operating income of $30,000. Which of the following statements is true, if Armstrong's inventory levels decrease during the accounting period?

A. Absorption costing will report less operating income than variable costing.

B. Variable costing will report less operating income than absorption costing.

C. Variable costing and absorption costing will report the same operating income since the total costs are the same.

D. Variable costing and absorption costing will report the same operating income since the cost of goods sold is the same.