The total contribution margin is calculated as the difference between

A) sales price and variable cost per unit.
B) sales price and fixed cost per unit.
C) total revenue and total variable cost.
D) total revenue and total cost.

Contribution margin represents the amount of revenue that is left over after deducting variable costs. Therefore, it is calculated as the difference between total revenue and total variable costs. Option A is incorrect because it only considers the contribution margin per unit. Option B is incorrect because fixed costs are not included in the calculation of contribution margin. Option D is incorrect because it includes all costs, including fixed costs, which are not relevant for calculating contribution margin.