Which key factor or factors contributed to the rise and growth of rock-and-roll music?

Radio sought a new audience after World War II.

Youths with money were looking for escapism and a new music style to identify their generation.

Desegregation and the beginnings of the Civil Rights movement brought about a blending of black and white cultures in U.S. society.

Is it even part of math

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.