The statement that must be true about the two postal delivery workers is: They each have a displacement of 0 miles.
Displacement refers to the overall change in position from the starting point to the ending point, and since both workers start and end at the post office, their displacement is indeed 0 miles.
The other statements are not necessarily true:
- They do not have to have the same velocity, as their speeds and directions can differ.
- They each travel a distance of 0 miles is incorrect because they travel to various neighborhoods.
- They travel the same distance is also incorrect, as the routes taken by each delivery worker may vary.