What is the domain of the function f(x)=(x^2-36)/(x-6)?
A) (-[infinity], 6) U (6, [infinity])
B) (-[infinity], -6) U (-6, 6) U (6, [infinity])
C) (-[infinity], -6) U (6, [infinity])
D) (-[infinity], 6) U (-6, 6) U (6, [infinity])