You were hired as a consultant to Quigley Company, whose target capital structure is $35\%$ debt, $10\%$ preferred, and $55\%$ common equity. The interest rate on new debt is $6$ retained earnings is $10\mathrm{.}50\%,$ and the tax rate is $25\%.$ The firm will not be issuing any new stock. What is Quigley's WACC? Round final answer to two decimal places.

a$.7\mathrm{.}13\%$

b$.7\mathrm{.}48\%$

c$.8\mathrm{.}08\%$

d$.6\mathrm{.}49\%$

e$.8\mathrm{.}65\%$