Answer
Александр
The correct choice:
Iris
While Iris takes 10 steps of length "X", Alice takes 11 steps of length "0.9*X" (because her steps are 10% shorter).
From this it turns out that for the same time Iris runs "10X", and Alice runs "9.9*X".
By the same method you can cross out Viola.
Iris is faster than the others.