The contribution margin is: Oa. equal to sales. Ob. equal to total costs. Oc. the difference between target income and operating income. Od. the difference between operating income and margin of safety. e. the difference between sales and variable expense. Identify the formula that computes the degree of operating leverage (DOL). Oa. Break-even sales/Variable cost ratio Ob. Total contribution margin / Operating income Oc. Unit variable cost/Price Od. Total variable cost/Sales Oe. Sales/Unit contribution margin