Musicologist: Classification of a musical instrument depends on the mechanical action through which it produces music. So the piano is properly called a percussion instrument, not a stringed instrument. Even though the vibration of the piano' s strings is what makes its sound, the strings are caused to vibrate by the impact of hammers. Which one of the following most accurately expresses the main conclusion of the musicologist's argument? ['Musical instruments should not be classified based on the way musicians interact with them.', 'It is correct to classify the piano as a percussion instrument rather than as a stringed instrument.', 'The piano should be classified as a stringed instrument rather than as a percussion instrument.', 'Some people classify the piano as a stringed instrument because of the way the piano produces sound.']