I might be wrong but I think C ( what the wave it traveling through). I think C because a wave medium is the substance that carries a wave (or disturbance) from one location to another. The wave medium is not the wave itself and it doesn’t make the wave. It just Carries or transports the wave from its source to other locations.
Yeah that's possible in some rare cases
Answer:
Genetic variation that alter gene activity or protein function can introduce different traits in an organism. If trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (a process known as natural selection).
friction is a force that opposes motion and significantly slows the cars as they move on the track. While it is easy to believe that friction is bad for the ride, it is one of the forces engineers consider in ensuring passengers have a safe ride.