Question: Which NBA head coach hold the record for the most championships won by an athlete in North America?

Context paragraphs:
Bill Russell: William Felton Russell (born February 12, 1934) is an American retired professional basketball player.  Russell played center for the Boston Celtics of the National Basketball Association (NBA) from 1956 to 1969.  A five-time NBA Most Valuable Player and a twelve-time All-Star, he was the centerpiece of the Celtics dynasty, winning eleven NBA championships during his thirteen-year career.  Russell holds the record for the most championships won by an athlete in a North American sports league (tied with Henri Richard of the National Hockey League).  Before his professional career, Russell led the University of San Francisco to two consecutive NCAA championships (1955, 1956), and he captained the gold-medal winning U.S. national basketball team at the 1956 Summer Olympics.

Paul Westhead: Paul William Westhead (born February 21, 1939) is an American basketball coach who most recently was the head coach of the University of Oregon women's team.  In his first year as an NBA head coach, he led a rookie Magic Johnson and the Los Angeles Lakers to the 1980 NBA Title.  He has previously been a head coach for three National Basketball Association (NBA) teams and an assistant for four others, and has also coached in the National Collegiate Athletic Association (NCAA), Women's National Basketball Association (WNBA), American Basketball Association (ABA) and Japan Basketball League (JBL).  He won titles in both the NBA and WNBA, and is also remembered as the coach of the Loyola Marymount University (LMU) men's basketball team during that school's era of greatest basketball glory.  Westhead is known for an unorthodox, run-and-gun style called "The System."  He attended Saint Joseph's University.

Mike Dunleavy Jr.: Michael Joseph Dunleavy Jr. (born September 15, 1980) is an American professional basketball player who last played for the Atlanta Hawks of the National Basketball Association (NBA).  He has previously played for the Golden State Warriors, Indiana Pacers, Milwaukee Bucks, Chicago Bulls and Cleveland Cavaliers.  He is the son of long-time NBA player and former NBA head coach Mike Dunleavy Sr.

2009 Detroit Shock season: The 2009 WNBA season is the 12th for the Detroit Shock of the Women's National Basketball Association in the United States.  The Shock attempted to win the WNBA Finals, tying the record for most championships with the Houston Comets (4), but failed in the conference finals.  On June 15, 2009, head coach Bill Laimbeer resigned as head coach of the Detroit Shock, due to family reasons and the desire to become an NBA head coach.  Though he was unable to secure an NBA head coaching position, ESPN reported on August 30 that Laimbeer was offered, and accepted, an assistant coach position with the Minnesota Timberwolves.  Despite the early struggles, the 2008 champion Detroit Shock reached the playoffs for the seventh straight year.  It would be the final year in Detroit, as the Shock were purchased by Tulsa Hoops, and new ownership moved the team to Tulsa for 2010.

K. C. Jones: K. C. Jones (born May 25, 1932) is an American retired professional basketball player and coach.  He is best known for his association with the Boston Celtics of the National Basketball Association (NBA), with which he won eleven of his twelve NBA Championships (eight as a player, one as an assistant coach, and two as a head coach).  As a player, he is tied for third for most NBA championships in a career, and is one of three NBA players with an unsurpassed 8-0 record in NBA Finals series outcomes.  He is the only African-American non-player head coach to win multiple NBA Finals.

Phil Jackson: Philip Douglas Jackson (born September 17, 1945) is a former American professional basketball player, coach and executive in the National Basketball Association (NBA).  Jackson was the head coach of the Chicago Bulls from 1989 until 1998, during which time Chicago won six NBA championships.  He then coached the Los Angeles Lakers, who won five championships from 2000 until 2010.  In total, Jackson has won 11 NBA titles as a coach, surpassing the previous record of nine set by Red Auerbach.  He also won two championships as a player with the New York Knicks in 1970 and 1973, and holds the NBA record for the most combined championships (13)

1974–75 Seattle SuperSonics season: The 1974–75 Seattle SuperSonics season was the 8th season of the Seattle SuperSonics in the National Basketball Association (NBA).  In their second season with Bill Russell as head coach and with rookies comprising half the roster, the SuperSonics finished the regular season in 4th place in the Western Conference with a 43–39 record and reached the playoffs for the first time in franchise history.  After defeating the Detroit Pistons in 3 games in the first round in a best-of-three series, the team fell to the future champions Golden State Warriors in six games.

Coby Karl: Coby Joseph Karl (born June 8, 1983) is an American professional basketball coach and former American basketball player who is currently head coach for the South Bay Lakers of the NBA G League.  He is the son of NBA head coach George Karl.

Stephen Silas: Stephen Silas is an American basketball coach, currently working as the lead assistant coach for the Charlotte Hornets of the National Basketball Association (NBA).  He is the son of longtime NBA head coach Paul Silas.

Eric Musselman: Eric Patrick Musselman (born November 19, 1964) is an American basketball coach, who is the current head coach at the University of Nevada, Reno.  He is the former head coach of the Sacramento Kings and Golden State Warriors of the National Basketball Association (NBA).  Between head coaching stints at Golden State and Sacramento, Musselman served as an assistant for the Memphis Grizzlies under Mike Fratello.  He moved to the college coaching ranks in 2012 as an assistant at Arizona State.  The son of former NBA head coach Bill Musselman, Eric Musselman was a head coach in the Continental Basketball Association (CBA) before becoming an assistant coach with the Minnesota Timberwolves, Orlando Magic (under Chuck Daly and Doc Rivers), and Atlanta Hawks (under Lon Kruger).

Supporting paragraphs: 1974–75 Seattle SuperSonics season Bill Russell
Answer: Bill Russell