Answer: D. You should authorize the $10,000 expenditure to continue the project if the project will generate a positive net present value. The marginal cost-benefit analysis treats the $2.5 million as a cost that is irrelevant to the current decision making.
Explanation:
The options you presented were not all the options listed. The option I have listed as the answer is the correct option.
Under the Marginal Cost - Benefit analysis, only the Additional costs and inflows are considered. The original cost is considered a Sunk Cost and therefore irrelevant.
When making a decision therefore, the company or person should ask if the new investment will bring about a positive NPV. If it is not anticipated to, then there is no need to invest more into it.