Boots Inc. has $500$ bonds with a face value of $$1,000$ each and a market value of $$950.$ The market interest rate for bonds with the same term and risk is $4\%.$ Boots Inc. has a tax rate of $30\%.$ Calculate Boots Inc.$\text{'}$s cost of debt after tax.

a$.2\mathrm{.}8\%$

b$.1\mathrm{.}2\%$

c$.10\%$

d$.5\%$