The channel is made of wood and has a downward slope of 0.0015. Find the depth of flow y that will produce the maximum volumetric flow using the least amount of wood when it is flowing full of water, that is, when y=h. What is this volumetric flow?
a. 4.72 ft³/s
b. 5.18 ft³/s
c. 4.35 ft³/s
d. 3.91 ft³/s