Answer:
C) negative at a discount rate of 20%.
Step-by-step explanation:
IRR is the interest rate at which the present value of the project or investment becomes zero. The discount rate above this rate will result the negative NPV and Below this rate will result the positive NPV.
10% is lower than the IRR of 15%, so the NPV should be positive.
20% is higher than the IRR of 15%, so the NPV should be negative.
15% is equal to the IRR of 15%, so the NPV should be zero.