An echo is formed when sound waves bounce off a flat surface. Therefore, the correct response is: Sound waves bounce off a flat surface.
How is an echo formed?(1 point) Responses Light waves go around a smooth surface. Light waves go around a smooth surface. Sound waves bounce off a flat surface. Sound waves bounce off a flat surface. Sound waves travel into a soft surface. Sound waves travel into a soft surface. Light waves pass through a shiny surface.
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