(Answered) Costs that cannot be avoided, because they have already been incurred are known as a. sunk costs….

➤ How do sunk costs differ from opportunity costs or marginal costs?
Unlike opportunity cost, which measures the next-best alternative forgone, sunk cost is past and irretrievable. Differential cost compares future changes between alternatives. Marginal cost shows the cost to produce one additional unit. Use sunk cost only to explain past accounting; use opportunity, differential, and marginal costs for current decisions.