The capital budgeting committee of the Caldwell Pipe Corporation is evaluating the possibility of replacing its old pipe-bending machine with a more advanced model. Information on the existing machine and the new model follows: Refer to Caldwell Pipe Corporation. The $80,000 market value of the existing machine is Select one: a. an opportunity cost of selling the old machine b. irrelevant to the equipment replacement decision c. a sunk cost d. a historical cost