Find and Simplify the Difference Quotient $$\frac { f ( x + h ) - f ( x ) } { h } , h \neq 0$$

Multiple Choice

Find and simplify the difference quotient $$\frac { f ( x + h ) - f ( x ) } { h } , h \neq 0$$ for the given function.
- $$f ( x ) = \frac { 1 } { 5 x }$$

A) $\frac { 1 } { 5 x }$
B) 0
C) $\frac { - 1 } { x ( x + h ) }$
D) $\frac { - 1 } { 5 x ( x + h ) }$