Which of the Following Formulas Would Be Best for Calculating $\frac{\text { unit price - variable cost per unit }}{\text { unit price }}$

Multiple Choice

Which of the following formulas would be best for calculating the total contribution margin?

A) sales revenue - total variable cost
B) $\frac{\text { unit price - variable cost per unit }}{\text { unit price }}$
C) price per unit - total cost per unit
D) $\frac{\text { revenueper product }}{\text {overall revenue }}$