Chandler, Inc., would like to buy one of the light fixtures its produces. The cost to buy the fixture is $$15$ per unit. The cost to make the fixture is $$13$ per unit. If the company buys, it can rent out the factory space it is no longer using for $$75,000$ annually. In this situation, the $$75,000$ is a$($n$)$:

sunk cost.

irrelevant cost.

avoidable cost.

opportunity cost.