A Trough Is to Be Made with an End of the Dimensions

Multiple Choice

A trough is to be made with an end of the dimensions shown. The length of the trough is to be 19 feet long. Only the angle $\theta$ can be varied. What value of $\theta$ will maximize the trough's volume?

A) $49^{\circ}$
B) $32^{\circ}$
C) $11^{\circ}$
D) $30^{\circ}$