A suitcase rests on the overhead rack of a bus moving at a constant 18 m/s north relative to the ground. For which one of the following observers does the suitcase appear to be at rest?
A. A cyclist traveling north at 8 m/s relative to the ground
B. A pedestrian standing on the sidewalk
C. A passenger seated on the bus
Identify the correct observer (A, B, or C) and state one brief reason.