Question: At which airport does the low-cost airline, a subsidiary of KLM founded by John Nicolaas Block, have its main base?
Context: EUjet was a low-cost airline based at Shannon Airport, Ireland.  It operated a network of services from its main base at Shannon Airport (SNN), with a hub at Kent International Airport (MSE), Manston, Kent, UK.  The airline was sold to a British company, PlaneStation, which also owned Kent airport, for €10m.  In July 2005, PlaneStation went out of business with €40m in debts, forcing EUjet to cease operations. Air Next Co., Ltd. (エアーネクスト株式会社 , Eā Nekusuto Kabushiki-gaisha ) was a low-cost airline based on the grounds of Fukuoka Airport in Hakata-ku, Fukuoka, Fukuoka Prefecture, Japan and a wholly owned subsidiary of All Nippon Airways (ANA).  It operated domestic services from its main base at Fukuoka Airport.  On October 1, 2010, Air Next, Air Central and Air Nippon Network were merged and rebranded as ANA Wings. Transavia, legally incorporated as "Transavia Airlines C.V." and formerly branded as "transavia.com", is a Dutch low-cost airline and a wholly owned subsidiary of KLM and therefore part of the Air France-KLM group.  Its main base is Amsterdam Airport Schiphol and has further bases at Rotterdam The Hague Airport, Munich Airport and Eindhoven Airport.  Transavia maintains Transavia France as its French subsidiary. Cebu Air, Inc., operating as Cebu Pacific (), is a Philippine low-cost airline based on the grounds of Ninoy Aquino International Airport (NAIA Terminal 3), Pasay City, Metro Manila, in the Philippines.  It offers scheduled flights to both domestic and international destinations.  Its main base is Ninoy Aquino International Airport, Manila, with other hubs at Mactan-Cebu International Airport, Clark International Airport, Kalibo International Airport Francisco Bangoy International Airport, and Iloilo International Airport. Eastar Jet (ESR) () is a low-cost airline with its headquarters in Banghwa-dong, Gangseo-gu, Seoul, South Korea.  On January 7, 2009, Eastar Jet made its maiden flight from Gimpo International Airport to Jeju International Airport.  Now, the airline operates a scheduled passenger network to 14 destinations in eight countries.  Its main base is Gimpo International Airport, with a hub at Jeju International Airport. Johan Nicolaas Block (May 18, 1929, Amsterdam – April 11, 1994) was a Dutch aviation pioneer.  He was the co-founder of Martinair, founder of Transavia and Air Holland. Centralwings was a charter airline based in Warsaw, Poland.  The airline operated as a low-cost airline and then became a charter-only operation in October 2008.  It was a subsidiary of LOT Polish Airlines, operating international services in Europe, using Boeing 737 aircraft.  Its main base was Warsaw Frederic Chopin Airport, with hubs at Gdańsk Lech Wałęsa Airport and John Paul II International Airport Kraków-Balice.  On 26 March 2009 the board of LOT Polish Airlines decided to close Centralwings with no information about what was to happen to its employees. Nordic Airways was an airline based in Stockholm, Sweden.  It operated extensive charter and wet lease services.  The company's low-cost airline subsidiary Nordic Regional also operates a scheduled network of services linking five domestic and one international destination.  Its main base was Stockholm-Arlanda Airport. Tiger Airways Australia Pty Ltd, operating as Tigerair Australia, is an Australian low-cost airline.  It commenced services in the Australian domestic airline market on 23 November 2007 as Tiger Airways Australia.  It is a fully owned subsidiary of Virgin Australia Holdings.  The airline is based in Melbourne, Victoria, with its main base at Melbourne Airport.  The Civil Aviation Safety Authority of Australia (CASA) grounded the airline in 2011; as a result operating bases at Adelaide and Avalon were shut down and it initially only operated out of its Melbourne base after returning to the air.  On 7 March 2012, Tigerair announced the reopening of a second base at Sydney Airport. Cebgo, Inc., operating as Cebgo, is a low-cost airline serving the Philippines.  It is the successor company to SEAir, Inc., which previously operated as South East Asian Airlines and Tigerair Philippines.  It is now owned by JG Summit, the parent company of Cebu Pacific which operates the airline.  Its main base has been transferred from Clark International Airport (formerly Diosdado Macapagal International Airport), Angeles to Ninoy Aquino International Airport, Metro Manila.
Answer: Amsterdam Airport Schiphol