$\text { Find the derivative of the function } f ( x ) = 9 \sqrt { x } \sin ( x ) \text {. }$

Multiple Choice

$\text { Find the derivative of the function } f ( x ) = 9 \sqrt { x } \sin ( x ) \text {. }$

A) $\frac { 9 } { 2 } \sqrt { x } \sin ( x ) + 9 \sqrt { x } \cos ( x )$
B) $\frac { 9 } { 2 \sqrt { x } } \sin ( x ) + 9 \sqrt { x } \cos ( x )$
C) $\frac { 9 } { 2 \sqrt { x } } \cos ( x )$
D) $\frac { - 9 } { 2 \sqrt { x } } \sin ( x ) + 9 \sqrt { x } \cos ( x )$
E) $\frac { 9 } { 2 \sqrt { x } } \sin ( x ) - 9 \sqrt { x } \cos ( x )$