<h2>Answer: Medium
</h2>
The medium is the main factor that differentiates a mechanical wave from an electromagnetic wave, since the first can not propagate without its existence, while the second can propagate regardless of whether the medium exists or not.
In addition, it is the medium that will define, the propagation speed of the wave, according to its specific physical characteristics.
Therefore, the <u>correct answer</u> is a.
Answer:
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Answer:
Explanation:
Arrangement of all known elements to men based on state of matter reactivity and valence shell structure
B. Kinetic energy increase, gravitational potential energy decreases