Question: "It took six years after the Metrobus' initial operation for what to open up?" Context: "The city's first bus rapid transit line, the Metrobus, began operation in June 2005, along Avenida Insurgentes. Line 2 opened in December 2008, serving Eje 4 Sur, line 3 opened in February 2011, serving Eje 1 Poniente, and line 4 opened in April 2012 connecting the airport with San Lazaro and Buenavista Station at Insurgentes. As the microbuses were removed from its route, it was hoped that the Metrobus could reduce pollution and decrease transit time for passengers. In June 2013, Mexico City's mayor announced two more lines to come: Line 5 serving Eje 3 Oriente and Line 6 serving Eje 5 Norte. As of June 2013, 367 Metrobus buses transported 850,000 passengers daily." Answer:
A:
line 3