Arectangular open box is to be made from $9m^2$ of cardboard. The maximum volume $($in $m^3)$ of such a box is

a$.\frac{5\sqrt[\phantom{2}]{3}}{2}$

b$.3$

c$.\frac{3\sqrt[\phantom{2}]{3}}{2}$

d$.\frac{\sqrt[\phantom{2}]{3}}{3}$

e$.4\sqrt[\phantom{2}]{3}$