The measurement of the expansion of the universe was what gave rise to the big bang theory and it's predictions.
I think it is b , that what I would i pick
The different reflections of light through two separate mediums causes the bending of wave fronts associated with light rays. The reflection and refraction is caused by the medium associated with its light rays.
Answer:
The dog ran a total distance of 45m but he is only 5m away from the starting line
Explanation: When you add 25 to 20 you get 45 for the total distance and if he ran back in the same direction then you would subtract 20 from 25 and get 5m