The Pro Division of Custom Industries is in need of a particular service. The service can be obtained from another division of Custom at "cost," with cost defined as the summation of variable cost ($9) and fixed cost ($3). Alternatively, Pro can secure the service from a source external to Custom for $10. Which of the following statements is true?

A. Pro should compare $10 versus $3 in deciding where to acquire the service.

B. Pro should compare $10 versus $9 in deciding where to acquire the service.

C. Pro should compare $10 versus $12 in deciding where to acquire the service.

D. From Custom's perspective, the proper decision is reached by comparing $10 versus $9.

E. Pro should both compare $10 versus $12 in deciding where to acquire the service and from Custom's perspective; the proper decision is reached by comparing $10 versus $9.