Final answer:
Doo-wop music of the 1950s was heavily influenced by gospel, blues, jazz, and R&B, combining vocal harmonies with the rhythm and structure of these genres.
Step-by-step explanation:
The key influence on the Doo-wop groups (vocal harmony) of the 1950s was a multifaceted blend of multiple musical styles, primarily drawing from genres such as gospel, blues, jazz, and R&B. The Doo-wop style emerged as a subgenre of R&B and featured vocal harmonies that were reminiscent of gospel music, while the structure and rhythm of the songs were often influenced by the blues and jazz. This new, exciting fusion captivated teenagers of the era, carving out its own identity in the burgeoning rock and roll scene.