$(8$ points$)$ A Norman window is a window in the shape of a rectangle surmounted by a semicircle whose diameter equals the base of the rectangle. What is the largest possible area of a Norman window with perimeter $4$ m $?$

A$.\frac{4}{4+}{m}^2$

B$.\frac{8}{4+}{m}^2($CORRECT$)$

C$.\frac{4}{4-}{m}^2$

D$.4+\frac{}{2}{m}^2$

E$.2m^2$