_______ was one of the most lucrative parts of the music business at the end of the nineteenth century.

AProviding music lessons
BSelling instruments
CGiving concerts
DWriting sheet music

Verified Answer :

"A. Providing music lessons" was one of the most lucrative parts of the music business at the end of the nineteenth century, since even some of the best composers turned to this field in order to make money.

It is not providing music lessons! I just took the test and got it wrong :(