Step-by-step explanation:
Displacement is the straight line distance from the starting position to the final position.
Person X walks halfway around circle. So her displacement is 100 m.
Person Y walks 3/4 of the way around. So his displacement is 50√2 m ≈ 70.7 m.
Person Z walks completely around the circle, so their displacement is 0 m.
Therefore:
Z < Y < X