Final answer:
Motown Sound was the bridge between pre-rock pop and the new black pop of the sixties, blurring racial lines and advancing the end of certain types of segregation.
Step-by-step explanation:
The bridge between pre-rock pop and the new black pop of the sixties was Motown Sound. The Motown Sound was a genre of music that emerged in the 1960s and was characterized by its combination of electric instruments with the sounds of gospel, blues, country, jazz, and R&B. It played a significant role in blurring racial lines and advancing the end of certain types of segregation across the nation.