What Is the Contribution Margin (CM) Ratio

What is the contribution margin (CM) ratio?

A) The difference between a company's sales revenues and variable costs, expressed as a percentage of sales revenues
B) The measurement of a company's direct operating leverage, expressed as a percentage of sales revenues
C) The difference between a company's sales revenues and production costs or cost of goods sold, expressed as a percentage of sales revenues
D) The difference between a company's sales revenues and net income after taxes, expressed as a percentage of sales revenues