Task: Question Generation
Input (English): On February 17, 2010, AF1 announced it would use the "Arena Football League" name. The league announced plans for the upcoming season and details of its contract with NFL Network to broadcast AFL games in 2010. AF1 teams were given the option of restoring historical names to their teams. In addition to the historical teams, the league added two new expansion franchises, the Dallas Vigilantes and the Jacksonville Sharks.
Output (English): How many expansion teams were announced in 2010?