Given the following information:

${}_{AB}=0\mathrm{.}313,{}_{BC}=0\mathrm{.}374,{}_{AC}=0\mathrm{.}321$

What is the expected return of the portfolio?

$0\mathrm{.}025$

$0\mathrm{.}012$

$0\mathrm{.}018$

$0\mathrm{.}015$

$0\mathrm{.}021$