
The Correct choice is : C. <u>Solids</u>
Sound waves need a medium to propagate, and the most suitable medium for that is solids, where it travel the fastest or with greatest efficiency.
Mercator projection is suitable for maritime navigation
The Mongols, a tribe of Nomads from Central or North Asia, who were ruled by Genghis Khan at the time.
The air and water are polluted
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