ontribution margin is the excess of sales over fixed costs." Do you agree? Explain. Question content area bottom Part 1 A. No. Contribution margin is the excess of sales over operating costs. B. No. Contribution margin is the excess of sales over all variable costs, not fixed costs. C. Yes. Contribution margin is the excess of sales over fixed costs. D. No. Contribution margin is the excess of sales over fixed costs and variable costs combined