Respuesta :
Answer:
I am pretty sure it is B My friend hope you are well
Explanation:
Answer:
B- It is a constant when the light is traveling in a vacuum.
Explanation:
"Light in a vacuum always travels at the same speed." Those additional three words in a vacuum are very important. A vacuum is a region with no matter in it. So a vacuum would not contain any dust particles (unlike a vacuum cleaner, which is generally full of dust particles)