The domain of the function \( f(x) := \dfrac{\cos^{-1}\!\left( \dfrac{x^{2} - 5x + 6}{x^{2} - 9} \right)}{\log_{e}(x^{2} - 3x + 2)} \) is:
\( (-\infty,\ 1) \cup (2,\ \infty) \)
\( (2,\ \infty) \)
\( \left[ -\dfrac{1}{2},\ 1 \right) \cup (2,\ \infty) \)
\( \left[ -\dfrac{1}{2},\ 1 \right) \cup (2,\ \infty) - \left\{ \dfrac{3 + \sqrt{5}}{2},\ \dfrac{3 - \sqrt{5}}{2} \right\} \)