The Appalachian mountains & the Rocky Mountains :)
Answer:
They all travel the same speed.
Explanation:
In the vacuum region , all the light or waves , travels at the same speed , i.e. , at 299,792 kilometers per second , due to the free space available without any obstruction or hindrance .
Being it to be X - rays , Visible light , Infrared light , all travel at the same speed ,
Hence , the correct answer to the statement given in question would be , They all travel the same speed .
This is true!! hope this helps. :)
