OBrien Ltd$.$s outstanding bonds have a $$1,000$ par value, and they mature in $25$ years. Their nominal yield to maturity is $9\mathrm{.}25\%,$ they pay interest semiannually, and they sell at a price of $$850.$ What is the bonds nominal $($annual$)$ coupon interest rate? a$6\mathrm{.}60\%$ b$6\mathrm{.}95\%$ c$6\mathrm{.}27\%$ d$7\mathrm{.}70\%$