The following is Addison Corporation's contribution format income statement for last month: Sales $1,000,000 Less variable 700,000 expenses 300,000 Contribution margin Less fixed 180,000 expenses Net income $ 120,000 The company has no beginning or ending inventories. A total of 20,000 units were produced and sold last month. Reference: Ref. 6-1 What is the company's margin of safety in dollars? Select one: O a. $600,000 O b. $400,000 O c. $880,000 O d. $120,000