Explain the single most important factor involved in advancing American classical music in the Twentieth Century.

The single most important factor in advancing American Classical Music in the 20th century was the development of jazz.

Jazz music help to influence the American culture.

 20th century classical music was focused on traditional rules and forms.

Sorry if i'm wrong!

development of jazz

The single most important factor in advancing American Classical Music in the 20th century was the development of jazz. Jazz music help to influence the American culture.

Explanation:

the answer is d. she became an english professor at university of georgia.