Letter B
without a medium, there is nothing to compress, hence, no wave. A fast- medium like a gas (air) is easy to compress and allows waves to move through it easily. a slow medium, like a liquid, is still pretty fast, but not as fast as air.
The answer is: Motion!
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A particle smaller than an atom or a <span>cluster of such particles </span>
To manage your money better, you can spend your money wisely. If you spend your money on smart things, your money managemnet skills will improve.
