Answer:
Option A - Sound waves must move through a substance
Explanation:
Unlike light waves, sound waves must travel through a medium/substance for such a medium to vibrate and then produce sound.
As a matter of fact sound can't travel through empty space.
Thus, looking at the options given, the correct one is:
Sound waves must move through a substance which is Option A
It will roll .. down the hill .. what else
The answer is D. the absolute correct answer is 36,000 making it three times hotter than the surface of the sun.
D. Ions are atoms that carry an electric charge.
I hope I was helpful!
Have an awesome day :)