Which of the following pairs of musical instruments produce sound due to the vibration of air column?

Analyze the question: We need the pair in which both instruments produce sound from a vibrating air column, which means they are wind instruments.

Concept: Musical instruments fall into groups by what vibrates:

• Strings (vibrating strings): guitar, violin, piano
• Percussion (vibrating solid or membrane): drum, bell
• Wind/aerophones (vibrating air column in a tube): flute, trumpet, organ (pipe organ), clarinet

Step by step:

• A. Bell and piano: The bell vibrates as a solid body, and the piano uses vibrating strings. Not correct.
• B. Guitar and flute: The guitar uses strings, so this pair is out.
• C. Trumpet and drum: The trumpet is an air column, but the drum uses a vibrating membrane. Not correct.
• D. Trumpet and flute: The trumpet is a brass wind instrument, and the flute is a woodwind. In both, the air inside the tube vibrates. Correct.
• E. Violin and organ: The organ (pipe organ) is an air column instrument, but the violin uses strings. Not correct.

Answer: D. Trumpet and flute.

Exam tip: Sort instruments into three groups: strings (guitar, violin, piano), percussion (drum, bell), and wind (flute, trumpet, organ). Then check that both instruments in the pair belong to the group the question asks for. Options with one wrong instrument, like E, are the usual trap.