Find the domain of $f\left(x\right)=\frac{1}{x^2-5x+6}$ . Express your answer using interval notation.

• A. Dom: $\left(-\infty,2\right)\cup\left(2,\infty\right)$
• B. Dom: $\left(-\infty,\infty\right)$
• C. Dom: $\left(-2,2\right)\cup\left(2,3\right)\cup\left(3,\infty\right)$
• D. Dom: $\left(-\infty,2\right)\cup\left(2,3\right)\cup\left(3,\infty\right)$