Given Functions F and G, Perform the Indicated Operations $( f g ) ( x )$

Multiple Choice

Given functions f and g, perform the indicated operations.
-Find the domain of $( f g ) ( x )$ when $f ( x ) = \sqrt { 5 x + 8 }$ and $g ( x ) = \sqrt { 6 x - 7 }$

A) Domain: $\left[ \frac { 7 } { 6 } , \infty \right)$
B) Domain: $[ 0 , \infty )$
C) Domain: $( - \infty , \infty )$
D) Domain: $\left[ - \frac { 7 } { 6 } , \infty \right]$