Find $( f \circ g ) ( x )$ $f ( x ) = x ^ { 2 } - 4 x \text {, and } g ( x ) = \sqrt { x + 9 }$

Multiple Choice

Find $( f \circ g ) ( x )$ . $f ( x ) = x ^ { 2 } - 4 x \text {, and } g ( x ) = \sqrt { x + 9 }$

A) $( f \circ g ) ( x ) = x + 9 - 4 \sqrt { x + 9 }$
B) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x }$
C) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x } + 9$
D) $( f \circ g ) ( x ) = \left( x ^ { 2 } - 4 x \right) \sqrt { x + 9 }$
E) $( f \circ g ) ( x ) = \sqrt { x ^ { 2 } - 4 x + 9 }$