select a option out of four

The following is last month's contribution format income statement Sales (15,000 Units) $375,000 Less: Variable Expenses $225,000 Contribution Margin $150,000 Less: Fixed Expenses $100,000 Operating Income $ 50,000 Using the degree of operating leverage concept, if the company's sales increase next year by 8%, by what percentage can its operating income expect to increase (within the relevant range)? 60% 36% 12% 24%