Which of the Following Best Describe the Term Degree of Operating

Which of the following best describe the term degree of operating leverage.

A) The percentage change in operating cash flow relative to the percentage change in quantity sold.
B) The sales level that results in a zero NPV.
C) Costs that do not change when the quantity of output changes during a particular time period.
D) The possibility that errors in projected cash flows lead to incorrect decisions.
E) Opportunities that managers can exploit if certain things happen in the future.