Consider the three following statements that concern two observers who are moving along the same line at different constant speeds with respect to an inertial frame. which of them are true? a. the observers will always disagree about the relative speed that each measures for the other's motion. b. the observers will always disagree about the length measured in the direction of the motion. c. the observers will always disagree about the time interval between two events.

option B and C

Explanation:

The correct answer is option B and C

the two observers are moving along the same line at different constant speed w.r.t inertial frame.

There will be argued on the length measured in the direction of motion and will also disagree about the time interval.

Time will be affected by the speed of motion as it's dependent on the speed.

Both of them will measure the same relative speed of each other. So, they won't disagree hence option A is not correct.