What makes wind energy "green"?
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A. It does not cost anything at all.
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B. It does not require farming.
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C. It does not work at night.
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D. It does not require burning anything.

What do electromagnetic waves carry? how are they produced through which media can they move? where do they transfer energy? what do they not transfer? what do mechanical waves carry? how are they produced? through which media can they move? where do they transfer energy? what do they not transfer?