Factor the Function Represented by F (X) and Explain How $f ( x ) = x ^ { 2 } - 4 x - 21$

Multiple Choice

Factor the function represented by f (x) and explain how the factored form relates to the graph of the function. $f ( x ) = x ^ { 2 } - 4 x - 21$

A) $f ( x ) = ( x + 3 ) ( x - 7 ) ; x = - 3$ and $x = 7$ represent the $y$ -intercepts.
B) $f ( x ) = ( x - 3 ) ( x + 7 ) ; x = 3$ and $x = - 7$ represent the $x$ -intercepts.
C) $f ( x ) = ( x - 3 ) ( x + 7 ) ; x = 3$ and $x = - 7$ represent the $y$ -intercepts.
D) $f ( x ) = ( x + 3 ) ( x - 7 ) ; x = - 3$ and $x = 7$ represent the $x$ -intercepts.