A capital projects 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 projects percentage internal rate of return based on these data is:

a.

16.12%

b.

13.29%

c.

14.63%

d.

15.27%