4 years ago, an investor bought a zero-coupon bond with a time-to-maturity of 5 years and a face value of $100 at the price of $50. Today, this investor decides to sell the bond, and the current one-year interest rate is 4%. Assuming that this bond has been fairly priced all the time, which of the followings is closest to this investor's realized compound yield during the period that he invested in this bond? Please round your calculation to the nearest 2nd decimal (i.e., percentage points). Select one: A. 18% B. 20% C. 22% D. 16% E. 14%