Determine Which of the Rational Functions Given Below Has the Following

Multiple Choice

Determine which of the rational functions given below has the following feature(s) .
-The x-axis is its horizontal asymptote

A) $f ( x ) = \frac { x - 2 } { x }$
B) $f ( x ) = \frac { x + 2 } { x + 9 }$
C) $f ( x ) = \frac { 2 x - 1 } { x + 9 }$
D) $f ( x ) = \frac { 9 } { x - 2 }$