SIROM Scientific Solutions has $$4$ million of outstanding equity and $$12$ million of bank debt. The bank debt costs $5\%$ per year. The estimated equity beta is $1.$ If the market risk premium is $9\%$ and the risk $-$ free rate is $4\%,$ compute the weighted average cost of capital if the firm's tax rate is $25\%.$

A$.6\mathrm{.}71\%$

B$.5\mathrm{.}8\%$

C$.5\mathrm{.}49\%$

D$.6\mathrm{.}1\%$