Final answer:
The string orchestra that performs the Air in Bach's Orchestral Suite No.3 traditionally includes the violin, viola, cello, and harpsichord, without the addition of gigue, oboe, or percussion instruments.
Step-by-step explanation:
The instruments that are added to the string orchestra that performs the Air in Bach's Orchestral Suite No.3 include the violin, viola, cello, and harpsichord. In the context of orchestral music, instruments like the violin, viola, and cello create resonance within their sounding boxes to amplify the sound produced by their vibrations. This is coupled with the harpsichord which, though a keyboard instrument, plucks strings internally and contributes to the ensemble's texture with its distinctive timbre. Unlike what may be suggested by option 1, 3, or 4, the work traditionally does not include the gigue, oboe, or percussion instruments as part of the orchestration for this particular movement.