Answer:
c. Irrelevant for decision-making purposes because, by definition, decisions do not influence these costs.
Explanation:
Sunk cost can be defined as a cost or an amount of money that has been spent on something in the past and as such cannot be recovered. Thus, because a sunk cost has been incurred by an individual or organization it can't be recovered and as such it is irrelevant in the decision-making process such as investments, projects etc.
Basically, sunk costs are referred to as fixed costs.
Hence, sunk costs are irrelevant for decision-making purposes because, by definition, decisions do not influence these costs.
