An echo is heard when sound is reflected off a surface. Which of the following best explains this phenomenon? O A. Sound waves strike a barrier and then spread out radially toward an observer
O B. Sound waves travel from one medium to another, bend, and travel back toward an observer
C. Sound waves bounce off a barrier and then travel back toward an observer
OD. Sound waves are absorbed and reemitted by a barrier. Then, the waves travel
back to an observer.
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