Nancy applies a force to a violin string by pulling her bow across it. The vibrations of the string produce sound waves, which cause the wooden portion of the violin to vibrate at its natural frequency.


The violin is designed so that a string vibrates at a frequency that matches the natural frequency of the wooden portion of the instrument. So repeatedly pulling the bow across this string allows _______ to occur.
A.
sound
B.
harmony
C.
muting
D.
resonance