Final answer:
The million-dollar sales of 'Swanee' can be attributed to its catchy melody, which resonated with a wide audience, making it a popular song of its time.
Step-by-step explanation:
The million-dollar sales of “Swanee” were primarily driven by its catchy melody. This song, made famous by Al Jolson, became a hit largely due to Jolson's dynamic performances and the appeal of the tune to a wide audience. While the song did incorporate some jazz elements, which were innovative at the time, and Jolson's performances could be considered an early form of innovative marketing, it was the melody that resonated most with listeners, leading to its immense popularity and high sales. The lyrics were not controversial, which can often attract attention but can also lead to sales being hampered, depending on public reaction. Therefore, the correct answer is A) Its catchy melody.