Find the Domain of X in the Expression $\sqrt { x ^ { 2 } - 4 }$

Multiple Choice

Find the domain of x in the expression.
$\sqrt { x ^ { 2 } - 4 }$

A) $( - \infty , 2 ] \cap [ 2 , \infty )$
B) $( - \infty , - 2 ] \cup [ 2 , \infty )$
C) $( - \infty , - 2 ] \cap [ 2 , \infty )$
D) $( - \infty , 2 ] \cup [ 2 , \infty )$
E) $( - \infty , - 2 ) \cup [ 2 , \infty )$