Which instrument sounds down a major second plus two octaves from written treble?

• A. Bb contra bass bass clarinet
• B. Eb alto clarinet
• C. Bb soprano clarinet
• D. Oboe

Answer: (A)

Understanding how transposing instruments relate written and sounding pitches is key. The B-flat contrabass clarinet is written as if in treble range, but its sounds come out two octaves lower plus a major second. In other words, every written treble note sounds two octaves and a second lower in concert pitch. The other options don’t pair with that interval: a B-flat soprano clarinet sounds a major second lower, an E-flat alto clarinet sounds a major sixth lower, and the oboe sounds at concert pitch with no transposition. So the instrument that matches sounding down a major second plus two octaves from written treble is the B-flat contrabass clarinet.