Final answer:
The magnitude of Edna's displacement is 0 meters.
Step-by-step explanation:
The magnitude of displacement is the distance between the starting point and the ending point, regardless of the path taken. In this case, Edna runs 28 meters north and then runs back to the south end of the court, which means her starting and ending points are the same. Therefore, the magnitude of her displacement is 0 meters (option b).