Which of the following is not true about Cost Volume Profit relationships?

A: All products are sold at the same price.

B: The cost drive for variable costs can be volume (units sold ) or the number of direct labor hours used in manufacturing one unit.

C: CVP can be used on multi-product companies if there is an assumption on the sales mix.

D: The costs must fall into either fixed or variable only . There are no mixed costs or non-linear costs.