1. How can a person sing into a piano and cause a piano wire to vibrate? A. The person sings at the same frequency as the piano wire, called the resonance frequency.

B. The person sings at a different frequency than the piano wire, called the beat frequency.

C. The person sings at the same frequency as the piano wire, called the beat frequency.

D. The person sings at a different frequency than the piano wire called the resonance frequency.

please help