Based on the following information, what is the firm's weighted average cost of capital of the non$-$operating assets, WACC ${?}_N?$

The firm:

Cost of debt, $R_D$:$5\%$

Cost of equity, $R_S$:$20\%$

Total market value of debt, D: $$800$

Yotal market value of equity, $S$:$$800$

Corporate tax rate, T: $40\%$

Operating assets:

Total market value, $0$:$$1,200$

Cost of debt, $RO{D}_{OD}$:$3\%$

Cost of equity, $R_{OS}$:$12\%$

a$.\mathrm{.}253$

b$.\mathrm{.}199$

c$.\mathrm{.}233$

d$.\mathrm{.}218$