Assume a Firm Has an Ongoing Need for a Machine

Assume a firm has an ongoing need for a machine and the current machine is operating efficiently.The firm should plan to replace this machine when it:

A) reaches the end of its depreciable life.
B) is fully paid for.
C) reaches a point where the book value is less than half of the original cost.
D) can be replaced with a machine that has a lower annual cost.
E) can be sold at a price that exceeds the current book value.