The first publicly available fantasy football league was launched in 1997, and within three years, every major football media website had launched their own sites. From 2000 until 2015, viewership for the National Football League rose by 27 percent, and it is currently the most popular televised sport in the United States. Fantasy football heavily contributed to the increased viewership since fantasy players had a vested interest in nearly every game. Upon which one of the following assumptions does the author's argument rely? ['Some fantasy players watch National Football League games.', "Fantasy football increased the play ers' knowledge of the National Football League.", 'Football was the least popular sport in the United States before 2000.', 'The National Football League earns a large portion of its revenue from high television ratings.']