Answer:
She is not moving.
Explanation:
It is stated that Pierre is observing both of them the same way which means that they are both moving in the same direction at the same speed, 4m/s. According to the relative speed concept, they will observe each other according to the difference in their movement directions and speed. Since they are moving in the same direction and at the same speed, Gabriella will be observed as if not moving from Michellle's point of view.
I hope this answer helps.
