All of the Following Are Assumptions Required to Perform Break-Even

All of the following are assumptions required to perform break-even and target profit calculations except:

A) Costs can be separated into fixed and variable components.
B) Contribution margin ratio remains constant for each product,segment,or department.
C) Break-even points can only be calculated for single product companies.
D) Sales mix remains constant with changes in sales volume.
E) None of the answer choices is correct.