JEE Math Practice Question

The domain of the function $$f(x) = {{{{\cos }^{ - 1}}\left( {{{{x^2} - 5x + 6} \over {{x^2} - 9}}} \right)} \over {{{\log }_e}({x^2} - 3x + 2)}}$$ is :

1. A.$$( - \infty ,1) \cup (2,\infty )$$
2. B.$$(2,\infty )$$
3. C.$$\left[ { - {1 \over 2},1} \right) \cup (2,\infty )$$
4. D.$$\left[ { - {1 \over 2},1} \right) \cup (2,\infty ) - \left\{ 3,{{{3 + \sqrt 5 } \over 2},{{3 - \sqrt 5 } \over 2}} \right\}$$