On January 1, $857,000, 5-year, 10% bonds, were issued for $831,290. Interest is paid semiannually on January 1 and July 1. If the issuing corporation uses the straight-line method to amortize discount on bonds payable, the semiannual amortization amount is Oa. 542,850 Ob. 525.710 Oc. 52,571 Od. 55.142