Suppose the following interest rates are given: one-year spot rate, y1, is 2% two-year spot rate, y2, is 9% forward rate from year one to year three, 1f3, is 14% forward rate from year two to year four, 2f4, is 20% Which one of the followings is closest to arbitrage-free four-year spot rate? (Please round your calculation to the nearest 2nd decimal, i.e., percentage point.) Select one: A. 14% B. 13% C. 12% D. 11% E, 10%