Find the domain of the function g(x)=\sqrt(x^(2)-9). Which of the following options correctly represents the domain of the function?
A) (-[infinity], -3] U [3, [infinity])
B) (-[infinity], -3) U (-3, 3) U (3, [infinity])
C) (-[infinity], -3) U [3, [infinity])
D) (-[infinity], -3] U (-3, 3) U [3, [infinity])