Final answer:
Prior to the electric bass, Rock & Roll bass players like Bill Black used the upright bass, a key instrument in blues, jazz, and country music, which were the roots of rock and roll.
Step-by-step explanation:
Before the introduction of the electric bass to Rock & Roll by Bill Black, the bass players in rock bands, including Bill Black himself, primarily used the upright bass, also known as the double bass. This acoustic instrument was a staple in earlier forms of music that heavily influenced rock and roll, such as blues, jazz, and country.
The transition to the electric bass was part of the transformation in the rock and roll genre, which merged the sounds of gospel, blues, country, jazz, and R&B, captivating teenagers and creating a new sound that defined a generation.