Let R be the region bounded by the following curves. Use the shell method to find the volume of the solid generated when R is revolved about the y-axis. y = 7x - x y = 7x- x. y=0 Set up the integral that gives the volume of the solid using the shell method. Use increasing limits of integration. Select the correct choice below and fill in the answer boxes to complete your choice. (Type exact answers.) O A. (2) dx O B. 2my ( 7x - y ? ) dy 343 The volume is 6 (Type an exact answer.)