The outstanding bonds of The Purple Fiddle are priced at $$898$ and mature in nine years. These bonds have a $6\%$ coupon and pay interest semi$-$annually. The firm's tax rate is $35\%.$ What is the firm's after$-$tax cost of debt?

a$.4\mathrm{.}93\%$

b$.3\mathrm{.}79\%$

c$.5\mathrm{.}30\%$

d$.7\mathrm{.}58\%$

e$.7\mathrm{.}61\%$