Once a company hits its break-even point, net operating income will

a. Increase by an amount equal to the selling price per unit multiplied by the number of units sold above the break-even point.

b. Increase by an amount equal to the contribution margin ratio multiplied by the number of units sold above the break-even point.

c. Increase by an amount equal to the contribution margin per unit multiplied by the number of units sold above the break-even point.

d. Increase by an amount equal to the variable cost per unit multiplied by the number of units sold above the break-even point.