One of the reasons that music publishing flourished was the growth of the middle class

True.

The music industry flourished due to the growth of the middle class that had the disposable income to afford buying music and to attend concerts. The changes in the tastes of Americans as the middle class expanded also led to a proliferation of various genres to serve the various tastes

what are local authorities doing to fix the problem

explanation:

what are local authorities doing to fix the problem