Final answer:
To determine which form of the minor scale Bach used, the presence and consistency of the raised sixth and seventh degrees must be examined; melodic minor features raised degrees when ascending and not when descending, harmonic minor has a consistently raised seventh, and natural minor has no alterations.
Step-by-step explanation:
To analyze the short melody to determine which form of the minor scale was used by J.S. Bach, one would need to examine the notes and chords used throughout the piece. Bach often utilized the melodic minor, harmonic minor, and natural minor scales in his compositions.
The melodic minor scale is characterized by a different ascending and descending pattern – the sixth and seventh degrees are raised when ascending and return to their natural minor form when descending. The harmonic minor scale maintains a raised seventh degree both when ascending and descending, which creates a distinctive 'leading tone' that resolves to the tonic. The natural minor scale maintains the same notes when ascending and descending, without altering any degrees of the scale.
If the melody contains a raised sixth and seventh degree while ascending but reverts to the natural minor form when descending, it is likely using the melodic minor. If the melody contains a consistently raised seventh degree, then it would suggest the use of the harmonic minor. The natural minor would not feature any alterations to the sixth or seventh degrees.