Final answer:
The most important financial concern for a Tin Pan Alley writer would have been royalties from sheet music sales and a focus on copyright protection to secure ongoing income from their music compositions.
Step-by-step explanation:
A Tin Pan Alley writer's most important financial concern would likely have been the royalties earned from sheet music sales and performances of their work. During the era of Tin Pan Alley, which was the center of the music publishing industry in the early 20th century, most songwriters made money through the sale of sheet music. Songs had to be popular and widely performed to generate significant income. Due to the popularity of live performances and radio at the time, if a song didn't catch on, there might be little to no financial gain. Considering the nature of creative industries, copyright protection was also crucial to ensure that writers maintained control over their work and continued to derive income from their compositions.