A(n) is a material that causes a wave to bounce off of it

Answer;

A barrier, a surface or a boundary

Explanation;

Reflection is the property waves that occurs due to the bouncing back of a wave after it strikes a barrier.

Reflection involves change in direction of a wavefront at an interface between two different media such that the wavefront returns into the medium from which it originated. In other words, the direction of the wave changes when they bounce of a barrier or a surface.

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