Five years ago, Robert Johnson Hotels purchased a machine for $$100,000.$ This machine suddenly stopped working. The company is debating whether to repair the machine or replace the old machine with a new one. Based on this decision, the initial $$100,000$ spent on the old machine is considered a$($an$)$:

Question $1$Select one:

a$.$

differential cost

b$.$

relevant cost

c$.$

sunk cost

d$.$

incremental cost