The change that signaled a musical progression toward rock and roll is C. An emphasis on back beat.
It should be noted that rock and roll originated in America mainly in the South. It was simply and offshoot of the blues.
In this case, the change that signaled a musical progression toward rock and roll is an emphasis on back beat.
In conclusion, the correct option is A.
Learn more about rock and roll on:
brainly.com/question/906043
#SPJ2