Answer:
A. Time and space are relative.
B. The speed of light in a vacuum is constant for all observers.
D. Physical laws change based on an observer's motion.
E. Physical laws remain constant regardless of an observer's motion.
Explanation:
21+10=31 because you can see that 21 and 10 are in metres while 12 is in seconds so 21+10=31 is the answer.
the main properties of the main wave propertioes include wavelength amplitude, cruest an trough