The domain the function $\sqrt {\log (x^2-6x+6)}$ is

Question

$\begin{array}{1 1} (-\infty, \infty) \\ (- \infty, 3 , - \sqrt 3) U (3+\sqrt 3 , \infty) \\(-\infty,1) U (5, \infty) \\(0, \infty) \end{array}$