Final answer:
The term for costs that a firm has to endure even with unsatisfactory investments is 'sunk costs' (c). These are irrecoverable past expenditures that should be disregarded when making future business decisions.
Step-by-step explanation:
Costs that a firm has to endure even when its investment turns out to be unsatisfactory are referred to as sunk costs. These costs represent money that has already been spent and cannot be recovered. Sunk costs can include expenses related to research and development, marketing, and production of goods that do not result in successful outcomes. Despite the frustration of dealing with sunk costs, the key lesson for firms is to disregard these past expenses and focus on future decision-making that can yield better results.
It is not uncommon for businesses to struggle with abandoning a project due to sunk costs, yet in the long run, decisions should be based on the potential for future revenues and profitability, not on unrecoverable past expenditures.