Possible Clues:

• D-sharp
• Black key on a piano
• What "Eroica" was written in
• Beethoven's 'Concerto No. 5 in ___ major'
• Key of Beethoven's Sonata No. 26
• Key in that piano song played with your knuckles
• Key of Beethoven's Piano Sonata No. 4
• Note near F
• Black key near D
• Note in a C minor triad