The 2nd one
i just guessed but my instincts tell me it's right, and they are usually right. But if u really need help explaining, go ask a teacher or parent!! i mean i'm a singer, NOT a geologist
Red Sea Reef, since a reef is a productive and diverse organism with different species of coral.
Having food means that there people won’t starve and can bring in trade
It should be a. Once fossil fuels are used we can not use them anymore.

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.