Find the Domain of X in the Expression $\sqrt { x ^ { 2 } - 7 x + 12 }$

Multiple Choice

Find the domain of x in the expression.​ $\sqrt { x ^ { 2 } - 7 x + 12 }$ ​

A) $( - \infty , 3 ] \cup [ 4 , \infty )$
B) $( - \infty , 3 ] \cap [ 4 , \infty )$
C) $( \infty , - 3 ] \cup [ 4 , \infty )$
D) $( \infty , 3 ] \cap [ 4 , \infty )$
E) $( \infty , - 3 ] \cap [ 4 , \infty )$