Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 13 to 20.

Baseball evolved from a number of different ball-and-stick games (paddle ball, trap ball, one-old-cat, rounders, and town ball) originating in England. As early as the American Revolution, it was noted that troops played “baseball” in their free time. In 1845 Alexander Cartwright formalized the New York Knickerbockers’ version of the game: a diamond-shaped infield, with bases ninety feet apart, three strikes – you’re – out, batter out on a caught ball, three outs per inning, a nine-man team. “The New York Game'' spread rapidly, replacing earlier localized forms. From its beginnings, baseball was seen as a way of satisfying the recreational needs of an increasingly urban–industrial society. At its inception, it was played by and for gentlemen. A club might consist of 40 members. The president would appoint two captains who would choose teams from among the members. Games were played on Monday and Thursday afternoons, with the losers often providing lavish evening entertainment for the winners. During the 1850 - 70 period the game was changing, however, with increasing commercialism (charging admission), under–the–table payments to exceptional players, and gambling on the outcome of games. By 1868 it was said that a club would have their regular professional ten, an amateur first-nine, and their” muffins“ (the gentle duffers who once ran the game). Beginning with the first openly all–salaried team (Cincinnati’s Red Stocking Club) in 1869, the 1870- 1890 period saw the complete professionalization of baseball, including the formation of the National Association of Professional baseball players in 1871. The National League of Professional Baseball Clubs was formed in 1876, run by business-minded inverters in joint-stock company clubs. The 1880s have been called Major League Baseball’s “Golden Age ''. Profits soared, players’ salaries rose somewhat, a season of 84 games became one of 132, a weekly periodical “The Sporting News” came into being, wooden stadiums with double-deck stands replaced open fields, and the standard refreshment became hot dogs, soda pop and peanuts. In 1900 the Western League based in the growing cities of the Midwest Proclaimed itself the American League.

The word “itself” in line 24 refers to____.