1. Cost-volume-profit analysis is based on certain general assumptions. Which of thefollowing is   not   one of these assumptions?
(A) Product prices will remain constant asvolume varies within the relevant range.
(B) Costs can be categorized as fixed, variable, orsemivariable.
(C) The efficiency and productivity of the production process and workerswill change to reflect manufacturing advances.
(D) Total fixed costs remain constant asactivity changes.
(E) Unit variable cost remains constant as activity changes.