Let $f\left ( x \right ) = \int_{0}^{x} e^{t}\left ( t-1 \right )\left ( t-2 \right )dt$. Then $f\left ( x \right )$ decreases in the interval

1. $x \in \left ( 1,2 \right )$
2. $x \in \left ( 2,3 \right )$
3. $x \in \left ( 0, 1 \right )$
4. $x \in \left ( 0.5, 1 \right )$