What is the relationship between reflection and diffraction? A. Reflection happens when a wave hits a hard surface, while diffraction only happens when a wave goes through air or water. B. Reflection happens when a wave hits a hard surface, while diffraction happens when two waves interact with each other. C. Reflection happens when a wave bounces back against an obstacle, while diffraction happens when a wave goes through an obstacle. D. Reflection happens when a wave bounces back against an obstacle, while diffraction happens when a wave bends around an obstacle.