Answer:
A. All motion is relative to the frame of reference chosen for measurement.
Step-by-step explanation:
Student 1 riding in the car is going at a certain speed. He sees the bus going a bit faster, so he thinks the bus is going at 20 km/h because to him, since he is also moving, it seems that the bus is only a little faster. Student 2 is on the sidewalk standing. He is not moving. When he sees the bus moving, the bus seems to be going fast because he is not moving. He estimates the speed of the bus to be 50 km/h.
The difference in estimates is due to their frames of reference.
Answer: A. All motion is relative to the frame of reference chosen for measurement.
