Which of the following is not an assumption underlying cost-volume-profit analysis? a. Product sales mix will not change during the period. b. The breakeven point will be reached and surpassed during the period. c. Cost behavior can be determined accurately. d. Productivity is constant within the relevant range. Which of the following is not an assumption underlying cost-volume-profit analysis? a. Product sales mix will not change during the period. b. The breakeven point will be reached and surpassed during the period. c. Cost behavior can be determined accurately. d. Productivity is constant within the relevant range