how to compute using a financial calculator

The cost of capital of Firm A is $12\mathrm{.}2$ percent compared to $17\mathrm{.}1$ percent for Firm B$.$ The market rate of return is $10\mathrm{.}8$ percent and the risk$-$free rate is $4$ percent. Firm A is considering the acquisition of Firm B$.$ Should this acquisition occur, it will be financed with debt at an interest cost of $8\mathrm{.}7$ percent. Which of these rates is most appropriate to use as the discount rate when analyzing the acquisition of Firm B by Firm A$?$

$8\mathrm{.}7\%$

$12\mathrm{.}2\%$

$10\mathrm{.}8\%$

$17\mathrm{.}1\%$

$4\mathrm{.}0\%$