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.
Answer:
Carbohydrates consist of the elements carbon (C), hydrogen (H) and oxygen (O) with a ratio of hydrogen twice that of carbon and oxygen. Carbohydrates include sugars, starches, cellulose and many other compounds found in living organisms. In their basic form, carbohydrates are simple sugars or monosaccharides.
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This works because the white pain acts as a barrier, therefor the sunlight a bounces off the glass instead of just going through.