Question $8\mathrm{.}19-$ A simply$-$supported wood beam is subjected to the maximum bending moment of $20$ kip $-$ ft $.$ If the beam is $6-$in wide and $12$ in deep, the maximum bending stress in the beam $($psi$)$ is most nearly:

A$.139$

B$.1,333$

C$.1,667$

D$.3,333$