The current market price of a company$$s $10\%$ coupon irredeemable debentures is $90$ per $100$ nominal. The company is paying corporation tax at a rate of $30\%.$

The current cost of debt per annum is

A$.$

$7\mathrm{.}7\%$

B$.$

$10\mathrm{.}0\%$

C$.$

$11\mathrm{.}1\%$

D$.$

$7\mathrm{.}4\%$