Final answer:
The lineup of musicians that established the definitive bluegrass sound is b. Bill Monroe, Earl Scruggs, Lester Flatt, Chubby Wise, and Cedric Rainwater.
Step-by-step explanation:
The lineup of musicians that established the definitive bluegrass sound known today is option b. Bill Monroe, Earl Scruggs, Lester Flatt, Chubby Wise, Cedric Rainwater.
Bill Monroe is widely known as the father of bluegrass music and his band, The Blue Grass Boys, featured Earl Scruggs on the banjo and Lester Flatt on the guitar. These two musicians revolutionized the bluegrass sound with Scruggs' innovative three-finger banjo picking style and Flatt's smooth, powerful vocals.
Chubby Wise played the fiddle, adding another essential element to the bluegrass sound, while Cedric Rainwater (later known as Howard Watts) played the bass, providing the rhythmic foundation for the band.