Set Up and Evaluate the Definite Integral for the Area $y = \frac { x } { 2 } , 1 \leq x \leq 9$

Multiple Choice

Set up and evaluate the definite integral for the area of the surface formed by revolving the graph of $y = \frac { x } { 2 } , 1 \leq x \leq 9$ about the $x$ -axis.

A) $40 \sqrt { 5 } \pi$
B) $4 \sqrt { 5 } \pi$
C) $20 \sqrt { 5 }$
D) $4 \sqrt { 5 }$
E) $20 \sqrt { 5 } \pi$