Which are examples of resonance? Check all that apply.

the volume on a stereo being turned up

a note being played on a saxophone

an opera singer breaking a glass with her voice

a person pushing a swing at the rate it naturally oscillates back and forth

an echo

By definition, a resonation is the resulting frequency of a vibrating object wherein it is in accordance with the periodic force applied to the object. Therefore, the best example of resonance among the choices provided would be " a person pushing a swing at the rate it naturally oscillates back and forth."