Timbukt, Inc. has annual bond payment liabilities of $10 million at the end of the next five (5) years. The firm intends to immunize the bond issuance via two zero-coupon issues with one (1) and four (4) years maturity. Assume a flat yield curve with 8% interest throughout the relevant period. Determine the percentage of zero coupons to be allocated to the four-year bonds in order to immunize the original bond portfolio. Select one: a. 84.4% b. 61.7% c. 39.2% d. 98.3%