Find the Derivative Of $f ( x ) = ( x - \sqrt { x } ) ( x + \sqrt { x } )$

Find the derivative of $f ( x ) = ( x - \sqrt { x } ) ( x + \sqrt { x } )$ .

A) $\left( 1 - \frac { 1 } { \sqrt { x } } \right) \left( 1 + \frac { 1 } { \sqrt { x } } \right)$

B) $2 x - 1$
C) $\left( 1 - \frac { 1 } { 2 \sqrt { x } } \right) \left( 1 + \frac { 1 } { 2 \sqrt { x } } \right)$
D) $2 x + 1$
E) $\left( 1 - \frac { 1 } { 2 \sqrt { x } } \right) \left( 1 + \frac { 1 } { \sqrt { x } } \right)$
F) $x - 1$

G) $\left( 1 - \frac { 1 } { \sqrt { x } } \right) \left( 1 + \frac { 1 } { 2 \sqrt { x } } \right)$

H) None of these