Question: Which subgenre of the blues is the performer of Fathers and Sons associated with?

full_context: Document 1: W. C. Handy: William Christopher Handy (November 16, 1873 -- March 28, 1958) was a composer and musician, known as the Father of the Blues. An African American, Handy was one of the most influential songwriters in the United States. One of many musicians who played the distinctively American blues music, Handy did not create the blues genre and was not the first to publish music in the blues form, but he took the blues from a regional music style (Delta blues) with a limited audience to a new level of popularity.
Document 2: The Real Folk Blues (Muddy Waters album): The Real Folk Blues is a 1966 compilation album of Muddy Waters recordings, released on the Chess record label in January 1966. The album was the first release of "The Real Folk Blues" series and has since been re-released on multiple formats. The album features some of Waters' first recordings.
Document 3: Robert Johnson: Robert Leroy Johnson (May 8, 1911 -- August 16, 1938) was an American blues singer - songwriter and musician. His landmark recordings in 1936 and 1937 display a combination of singing, guitar skills, and songwriting talent that has influenced later generations of musicians. Johnson's poorly documented life and death at age 27 have given rise to much legend. One Faustian myth says that he sold his soul to the devil at a local crossroads of Mississippi highways to achieve success. As an itinerant performer who played mostly on street corners, in juke joints, and at Saturday night dances, Johnson had little commercial success or public recognition in his lifetime.
Document 4: Forty Days and Forty Nights: "Forty Days and Forty Nights" is a blues song recorded by Muddy Waters in 1956. Called "a big, bold record", it was a hit, spending six weeks in the "Billboard" R&B chart, where it reached number seven. "Forty Days and Forty Nights" has been interpreted and recorded by a variety of artists.
Document 5: Howlin' Wolf: Chester Arthur Burnett (June 10, 1910 – January 10, 1976), known as Howlin' Wolf, was a Chicago blues singer, guitarist, and harmonica player, originally from Mississippi. With a booming voice and imposing physical presence, he is one of the best-known Chicago blues artists. The musician and critic Cub Koda noted, "no one could match Howlin' Wolf for the singular ability to rock the house down to the foundation while simultaneously scaring its patrons out of its wits." Producer Sam Phillips recalled, "When I heard Howlin' Wolf, I said, 'This is for me. This is where the soul of man never dies. Several of his songs, including "Smokestack Lightnin'", "Killing Floor" and "Spoonful", have become blues and blues rock standards. In 2011, "Rolling Stone" magazine ranked him number 54 on its list of the "100 Greatest Artists of All Time".
Document 6: Mandolin: Mandolin has also been used in blues music, most notably by Ry Cooder, who performed outstanding covers on his very first recordings, Yank Rachell, Johnny "Man" Young, Carl Martin, and Gerry Hundt. Howard Armstrong, who is famous for blues violin, got his start with his father's mandolin and played in string bands similar to the other Tennessee string bands he came into contact with, with band makeup including "mandolins and fiddles and guitars and banjos. And once in a while they would ease a little ukulele in there and a bass fiddle." Other blues players from the era's string bands include Willie Black (Whistler And His Jug Band), Dink Brister, Jim Hill, Charles Johnson, Coley Jones (Dallas String Band), Bobby Leecan (Need More Band), Alfred Martin, Charlie McCoy (1909-1950), Al Miller, Matthew Prater, and Herb Quinn.
Document 7: Chicago blues: The Chicago blues is a form of blues music indigenous to Chicago, Illinois. Chicago blues is an electric blues style of urban blues. Urban blues evolved from classic blues following the Great Migration, or the Great Northern Drive, which was both forced and voluntary at times, of African Americans from the southern United States to the industrial cities of the north, such as Chicago. Muddy Waters directly joined that migration, like many others, such as in Florida, avoiding the more harshly southern Jim Crow laws. Bruce Iglauer, founder of Alligator Records stated that, ``Chicago blues is the music of the industrial city, and has an industrial sense about it. ''Additionally, recognizing the shift in blues, Chicago blues singer and guitarist Kevin Moore expressed the blues transition stating,`` You have to put some new life into it, new blood, new perspectives. You ca n't keep talking about mules, workin 'on the levee.'' Chicago blues was heavily influenced by Mississippi bluesmen who traveled to Chicago in the early 1940s. The development of blues, up to Chicago blues, is arguably as follows: Country blues, to city blues, to urban blues. Chicago blues is based on the sound of the electric guitar and the harmonica, with the harmonica played through a PA system or guitar amplifier.
Document 8: Rollin' Stone: The Golden Anniversary Collection: Rollin' Stone: The Golden Anniversary Collection is a compilation album collecting the first 50 master recordings of blues singer Muddy Waters for Chess Records. The collection spans Muddy's debut with then named Aristocrat Records circa 1947, and traces his evolution as a songwriter and musician up to September 17, 1952 on what became Chess Records after the company changed ownership. It is the first in a series of releases chronicling Muddy Waters' complete recording career at Chess. The second release in the series is "" (2004) and the third release in the series is "" (2012).
Document 9: Folk Singer (album): Folk Singer is the fourth studio album by Muddy Waters, released in April 1964 by Chess Records. The album features Waters on acoustic guitar, backed by Willie Dixon on string bass, Clifton James on drums, and Buddy Guy on acoustic guitar. It is Waters's only all-acoustic album. Numerous reissues of "Folk Singer" include bonus tracks from two subsequent sessions, in April 1964 and October 1964.
Document 10: After the Rain (Muddy Waters album): After the Rain is the sixth studio album by Muddy Waters, a follow-up to the previous years' "Electric Mud" and sharing many of the musicians from that album. Unlike "Electric Mud", "After the Rain" contained mostly his own compositions and the songs, while still distorted, are less overtly psychedelic.
Document 11: Muddy Waters: McKinley Morganfield (April 4, 1913 -- April 30, 1983), known professionally as Muddy Waters, was an American blues musician who is often cited as the ``father of modern Chicago blues ''.
Document 12: Walkin' Blues: "Walkin' Blues" or "Walking Blues" is a blues standard written and recorded by American Delta blues musician Son House in 1930. Although unissued at the time, it was part of House's repertoire and other musicians, including Robert Johnson and Muddy Waters, adapted the song and recorded their own versions.
Document 13: Big Bill Morganfield: William "Big Bill" Morganfield (born June 19, 1956) is an American blues singer and guitarist, who is the son of Muddy Waters.
Document 14: King Bee (album): King Bee is the fourteenth and final studio album by blues singer and guitarist Muddy Waters. Released in 1981, it is third in a series of records done for the label Blue Sky Records under producer/guitarist Johnny Winter. Recorded in three days (and in the wake of Muddy's failing health) some of the band members, namely Winter and guitarist Bob Margolin, were not happy with the result. As his health deteriorated, Muddy was forced to cancel an increasing number of shows. He died of a heart attack on April 30, 1983.
Document 15: Fathers and Sons (album): Fathers and Sons is the seventh studio album by American blues musician Muddy Waters, originally released as a double LP by Chess Records in August 1969.
ground_truth: Chicago blues
sub_queries: Fathers and Sons >> performer Answer: Muddy Waters
Muddy Waters is associated with which subgenre of the blues Answer: Chicago blues