For the answer to the question, ergonomics<span> is the science of fitting the job to the worker. When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, work-related musculoskeletal disorders (MSDs) can result. Ergonomics is the practice of designing equipment and work tasks to conform to the capability of the worker, it provides a means for adjusting the work environment and work practices to prevent injuries before they occur.</span>
C because of the positioning of the initial ray of refraction
Boy X and Boy Y both move backward in opposite directions.
The answer is 60 km. I hope it helps i dont know if this is right or wrong.