b) Oklahoma!

Oklahoma!, a groundbreaking musical first performed in 1943, marked a significant turning point in American theater and set the stage for modern Broadway. This musical, blending classical and jazz styles, was revolutionary for its integration of song, dance, and narrative. Created by the legendary duo of Richard Rodgers and Oscar Hammerstein II, Oklahoma! introduced a new form of storytelling in musical theatre, where the music and choreography were integral to the development of the plot. Its success paved the way for numerous other productions and significantly influenced the evolution of the American musical.