Please answer the following question: Information:  - At the end of each Major League Baseball season, the league leaders of various statistical categories are announced. Leading the league in a particular category is referred to as a "title".  - The World Series is the annual championship series of Major League Baseball (MLB) in North America, contested since 1903 between the American League (AL) champion team and the National League (NL) champion team. The winner of the World Series championship is determined through a best-of-seven playoff, and the winning team is awarded the Commissioner's Trophy. As the series is played in October (and occasionally November), during the autumn season in North America, it is often referred to as the Fall Classic.  - Chicago (or ), officially the City of Chicago, is the third-most populous city in the United States, and the fifth-most populous city in North America. With over 2.7 million residents, it is the most populous city in the state of Illinois and the Midwestern United States, and the county seat of Cook County. The Chicago metropolitan area, often referred to as Chicagoland, has nearly 10 million people and is the third-largest in the U.S.  - The American League of Professional Baseball Clubs, or simply the American League (AL), is one of two leagues that make up Major League Baseball (MLB) in the United States and Canada. It developed from the Western League, a minor league based in the Great Lakes states, which eventually aspired to major league status. It is sometimes called the Junior Circuit because it claimed Major League status for the 1901 season, 25 years after the formation of the National League (the "Senior Circuit").  - The National Association of Professional Base Ball Players (NAPBBP), or simply the National Association (NA), was founded in 1871 and continued through the 1875 season. It succeeded and incorporated several professional clubs from the National Association of Base Ball Players (NABBP); in turn several of its clubs created the succeeding National League of Professional Baseball Clubs.  - The National League of Professional Baseball Clubs, known simply as the National League (NL), is the older of two leagues constituting Major League Baseball (MLB) in the United States and Canada, and the world's oldest current professional team sports league. Founded on February 2, 1876, to replace the National Association of Professional Base Ball Players, it is sometimes called the Senior Circuit, in contrast to MLB's other league, the American League, which was founded 25 years later. Both leagues currently have 15 teams. The two league champions of 1903 arranged to compete against each other in the inaugural World Series. After the 1904 champions failed to reach a similar agreement, the two leagues formalized the World Series as an arrangement between the leagues. National League teams have won 48 of the 112 World Series contested from 1903 to 2016. The 2016 National League champions are the Chicago Cubs.  - The Chicago Cubs are an American professional baseball team based in Chicago, Illinois. The Cubs compete in Major League Baseball (MLB) as a member club of the National League (NL) Central division, where they are the defending World Series champions. The team plays its home games at Wrigley Field, located on the city's North Side. The Cubs are one of two major league teams in Chicago; the other, the Chicago White Sox, is a member of the American League (AL) Central division. The team, first known as the White Stockings, was a founding member of the NL in 1876, becoming the Chicago Cubs in 1903.  - The Union Association was a league in Major League Baseball which lasted for only one season in 1884 . St. Louis won the pennant and joined the National League the following season . Chicago moved to Pittsburgh in late August , and four teams folded during the season and were replaced . Although the league is conventionally listed as a major league , this status has been questioned by a number of modern baseball historians , most notably Bill James in The Bill James Historical Baseball Abstract . The league had a number of major league players ( on the St. Louis franchise , at least ) , but the league 's overall talent and organization was notably inferior to that of the two established major leagues . James found that the contemporary baseball guides did not consider the Union Association to be a major league either . The earliest record he could find of the Union Association as a major league was Ernest Lanigan 's The Baseball Cyclopedia , published in 1922 . For example , the league 's only `` star '' player , Fred Dunlap , led the league in batting average with .412 ( 86 points higher than his second - best season and 120 points higher than his career average ) , on - base percentage , slugging percentage , runs scored , hits , total bases , and home runs ( with just 13 , typical for the era ) . After the league folded , Dunlap never hit more than .274 or more than 10 home runs until he retired in 1891 , another measure of the inferior quality of the Union Association . Of the 272 players in the Association , 107 ( 39.34 % ) never played in another major league , while 72 ( 26.47 % ) played very briefly ( less than 300 at bats and / or 50 hits ) in other major leagues , and 79 ( 29.04 % ) had longer careers but little success in other major leagues . A relatively modern comparison could be the World Football League of the early 1970s contrasted with the National Football League . The WFL similarly resorted to putting clubs in small cities or cities with established teams , and collapsed in the middle of a...    Given the paragraphs above, decide what entity has the relation 'instance of' with 'sports league'.
A:
union association