Aflash of light is sent simultaneously into two parallel tubes of length 1 km—one evacuated, the other filled with water. there is a detector to sense the arrival time of the light flash at the end of each tube. what will be the relationship between arrival times of these light flashes? (a) the flash will arrive earliest through the evacuated tube, and later through the water-filled tube.(b) the flash will arrive earliest through the water-filled tube, and later through the evacuated tube.(c) the flashes of light will arrive simultaneously at the ends of the tubes because light always travels at the same speed.(d) only the flash through the water-filled tube arrives, because light is a wave and cannot travel in a vacuum.