Which of the Following Are Underlying Assumptions of Cost-Volume-Profit Analysis

Which of the following are underlying assumptions of cost-volume-profit analysis?

A) Fixed costs will not change over a wide range of activity and variable costs are strictly variable.
B) All costs can be classified either as a fixed or variable cost and behave linearly.
C) Sales prices do not change in the relevant range and the sales mix must remain constant.
D) All of the answers are correct.