$13.$ ABC Soluticns has $$12$ million of outstanding equity and $$4$ million of bank debt. The bank debt costs $4\%$ per year. The estimated equity beta is $1\mathrm{.}0.$ If the market risk premium is $8\%$ and the risk$-$froe rate is $4\%,$ compute the weighted average cost of capital if the firm's tax rate is $20\%.$

a$.9\mathrm{.}66\%$

b$.98\%$

c$.9\mathrm{.}70\%$

d$.10\mathrm{.}67\%$

Please with clear calculations