Consider the Region Between the Graph Of $f ( x ) = \sqrt { x - 1 }$

Consider the region between the graph of $f ( x ) = \sqrt { x - 1 }$ and the x-axis on the interval [1,5].
-Using four disks or washers approximate the volume of the solid that is obtained by revolving this region around the x-axis.

A) 6 $\pi$
B) 7 $\pi$
C) 8 $\pi$
D) 9 $\pi$