Answer: Sunk cost
Step-by-step explanation:
Sunk cost is a cost that is incurred by an entity, which can not be recover. When making the decision on whether to continue investing in a project which is ongoing, the sunk costs should not be considered since these type of costs can't be recovered.
Sunk costs cannot be recovered or refunded. The 10 percent discussed in the question is a sunk cost as it can't be recovered.