Which of the following is a true statement regarding the contribution margin and the gross margin?
a.The gross margin is calculated by subtracting all variable costs from revenues.
b.The contribution margin is calculated by subtracting all product costs from revenues.
c. Direct materials and labor, variable manufacturing overhead and general overhead, and fixed manufacturing overhead are subtracted from revenues to determine the contribution margin.
d.The contribution margin is calculated by subtracting all variable costs from, revenues.