Which of the Following Would Be a Likely Mathematical Expression

Which of the following would be a likely mathematical expression for Total Variable Cost? ​ ​

A) Total Variable Cost = Production Volume × Revenue per Unit
B) Total Variable Cost = Material Cost per Unit × Labor Cost per Unit
C) Total Variable Cost = Total Cost - (Material Cost per Unit + Labor Cost per Unit)
D) Total Variable Cost = (Material Cost per Unit + Labor Cost per Unit) × Production Volume