15. Rovinsky Corporation, a company that produces and sells a single product, has provided its contribution format income statement for November. Sales (6,300 units) $ 403,200 Variable expenses 277,200 Contribution margin 126,000 Fixed expenses 103,500 Net operating income $ 22,500 If the company sells 6,200 units, its net operating income should be closest to: (Do not round intermediate calculations.) a. $21,979 b. $20,500 c. $22,500 d. $18,000