Final answer:
The degree of operating leverage is the percent change in operating income divided by the percent change in unit volume.
Step-by-step explanation:
The degree of operating leverage can be defined as the percent change in operating income divided by the percent change in unit volume. This is represented by option A in the question. The degree of operating leverage measures the sensitivity of operating income to changes in sales volume. It indicates the extent to which a company's operating income will change in response to a change in sales.