Calculate the required rate of return for Mercury Inc., assuming that the current risk$-$free rate is equal to $8$ percent and the return on the market is $13$ percent. Mercury has a beta of $2\mathrm{.}0,$ and its realized rate of return has averaged $15$ percent over the last $5$ years.

Group of answer choices

a$.15\%$

b$.16\%$

c$.17\%$

d$.18\%$

e$,20\%$