Answer
D. A sunk cost is any cost that was expended in the past but can be recovered if the firm decides not to go forward with the project.
Explanation:
As per the data given in the question,
Option (D) is correct among the given statements. A sunk cost is that cost which was occurred and expended in the past and if firm decides to do not go ahead, it can not be recovered.
For illustration - Think about the cost incurred to find out the feasibility of the project. Though in past firm was agree with the project but now even if the firm decides not to the project, this cost can not be recovered.