Final Answer:
2) The supertonic of B-flat minor is "re."
Step-by-step explanation:
In music theory, the supertonic is the second degree of a diatonic scale. In the context of B-flat minor, the B-flat natural minor scale consists of the following notes: B♭ - C - D♭ - E♭ - F - G♭ - A♭ - B♭. The supertonic is the second note, which is "C" in this case. Therefore, the correct answer is 2) "re."
Conclusion:
The supertonic of B-flat minor is the second note, which is represented by "re" in solfège or the second degree in the scale. The answer "2) re" accurately identifies the supertonic in the B-flat minor scale.