A capital project's cash flows have an NPV of minus 40 when discounted at a rate of 15% ; minus 60 when discounted at a rate of 20%; and plus 30 when discounted at a rate of 12%. The best approximation by linear interpolation of the project's percentage internal rate of return based on these data is: O a. 15.27% O b. 14.63% O c. 13.29% Od. 16.12%