Let R be the finite region bounded between y=x² and y=9x. Consider the solid whose base is the region R and whose cross-sections perpendicular to the x-axis are semicircles. Find the volume of this solid.

A) Calculate the area of region R and multiply it by the height of the solid.
B) Integrate the area of the semicircles along the x-axis over the region R.
C) Use the formula for the volume of a solid with semicircular cross-sections.
D) Divide the region R into small rectangles and sum up their volumes.

Note: Please remove unnecessary space and unnecessary words.