Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time \(t_1\). On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time \(​t_2\). The time taken by her to walk up on the moving escalator will be:

1. \(\dfrac{t_1-t_2}{2}\)

2. \(\dfrac{t_1t_2}{t_2-t_1}\)

3. \(\dfrac{t_1t_2}{t_2+t_1}\)

4.  \(t_1-t_2\)