Question: Which airport is closer to Washington D.C., Washington Dulles International Airport or Gainesville Regional Airport?

Context paragraphs:
Dulles Town Center: The Dulles Town Center (DTC) is a two-level enclosed shopping mall in Dulles, Loudoun County, Virginia, United States, located five miles north of the Washington Dulles International Airport.  The retail center gives its name to the census-designated place (CDP) within which it is located.  It encompasses 1400000 sqft of GLA and is the largest enclosed shopping center in Loudoun County.  The mall caters to the burgeoning and affluent population of eastern Loudoun and western Fairfax counties.  Dulles Town Center is anchored by Dick's Sporting Goods, J.C. Penney, Lord and Taylor, Macy's, Nordstrom, Sears and features an eclectic mix of upscale retailers such as Abercrombie & Fitch, Banana Republic, and LOFT.  In addition, the mall has been a launch pad for international retailers emerging into the U.S. market.  High-end New Zealand children's store Pumpkin Patch opened its second U.S. store and German restaurant chain Vapiano opened its third U.S. location at Dulles Town Center in 2007.  In 2015, Vapiano closed down and it's former spot is now unoccupied in the mall.

Dulles Town Center, Virginia: Dulles Town Center is a census-designated place (CDP) in Loudoun County, Virginia, located about seven miles north of Washington Dulles International Airport.  The population as of the 2010 United States Census was 4,601.  The CDP is the location of the Dulles Town Center shopping mall, for which it is named.  The United States Postal Service considers Dulles Town Center to be a subsection of Dulles, which is itself a subsection of Sterling; none of these locations is an incorporated municipality.

Gainesville Regional Airport: Gainesville Regional Airport (IATA: GNV, ICAO: KGNV, FAA LID: GNV) is a public airport three miles northeast of Gainesville, in Alachua County, Florida.  It is owned by Gainesville-Alachua Co.  Auth.  The National Plan of Integrated Airport Systems for 2011–2015 categorized it as a "primary commercial service" airport (more than 10,000 enplanements per year).

American Airlines Flight 77: American Airlines Flight 77 was a scheduled American Airlines domestic transcontinental passenger flight from Washington Dulles International Airport in Dulles, Virginia, to Los Angeles International Airport in Los Angeles, California.  The Boeing 757-223 aircraft serving the flight was hijacked by five men affiliated with al-Qaeda on September 11, 2001, as part of the September 11 attacks.  They deliberately crashed the plane into the Pentagon in Arlington County, Virginia, near Washington, D.C., killing all 64 people on board, including the five hijackers and six crew, as well as 125 people in the building.

Virginia State Route 267: State Route 267 is a primary state highway in the US state of Virginia.  It consists of two end-to-end toll roads – the Dulles Toll Road and Dulles Greenway – as well as the Dulles Access Road, which lies in the median of Dulles Toll Road and then extends east to Falls Church.  The combined roadway provides a toll road for commuting and a free road for access to Washington Dulles International Airport.  The three sections are operated and maintained by separate agencies: Dulles Toll Road and Dulles Access Road are maintained by the Metropolitan Washington Airports Authority (MWAA); the Dulles Greenway is owned by TRIPP II, a limited partnership, but is maintained by Macquarie Atlas Roads, an Australian company which owns the majority stake in the partnership.  The Dulles Access Road's median hosts the Silver Line of the Washington Metro for much of the length between Reston and Falls Church.

Air Wisconsin: Air Wisconsin Airlines is a regional airline based at Appleton International Airport in the town of Greenville, Wisconsin, United States, near Appleton.  Air Wisconsin is the largest privately held regional airline in the United States.  It currently operates regional jet flights as American Eagle under contract to American Airlines via a code sharing agreement, serving cities in the U.S. and Canada with hubs at Boston Logan International Airport (BOS), Charlotte Douglas International Airport (CLT), Philadelphia International Airport (PHL) and Ronald Reagan Washington National Airport (DCA) .  Air Wisconsin previously operated United Express service on behalf of United Airlines followed by US Airways Express service on behalf of US Airways prior to becoming an American Eagle regional air carrier.  The company has announced it will once again partner with United Airlines as a United Express code sharing air carrier with primary hubs to be located at Chicago O'Hare International Airport (ORD) and Washington Dulles International Airport (IAD) beginning in September 2017 and will be "exclusively operating" as United Express by March 2018.

Dulles International Airport station: Dulles International Airport is a planned Washington Metro station at Washington Dulles International Airport in Loudoun County, Virginia on the Silver Line.  It is scheduled to begin operation in 2020, linking Dulles by rail to Washington, D.C. and Ronald Reagan Washington National Airport via Rosslyn.  The station was originally planned to be underground, and feature a tunnel to the Dulles baggage claim area.  Current plans call for an above-ground station next to daily parking garage 1.

Baltimore–Washington International Airport: Baltimore/Washington International Thurgood Marshall Airport (IATA: BWI, ICAO: KBWI, FAA LID: BWI) is an international airport located in Linthicum in northern unincorporated Anne Arundel County, Maryland.  The airport is 9 miles south of downtown Baltimore and 32 miles northeast of Washington, D.C. It is the busiest, by passenger count, of three major airports serving the Baltimore–Washington metropolitan area in the United States, the other two being Ronald Reagan Washington National Airport and Washington Dulles International Airport.  It is commonly referred to as BWI or BWI Marshall.  The airport is named after Thurgood Marshall, a Baltimore native who became the first African American to serve on the Supreme Court of the United States.

USAfrica Airways: USAfrica Airways was a United States-based airline that operated flights between Washington Dulles International Airport (then called Dulles International Airport) and Johannesburg in starting in June, 1994.  Its headquarters was in Reston, Virginia, and it had an office in Washington, DC.

Washington Dulles International Airport: Washington Dulles International Airport (IATA: IAD, ICAO: KIAD, FAA LID: IAD) is an international airport in Loudoun and Fairfax counties in Virginia, United States, 26 miles (42 km) west of downtown Washington, D.C. The airport serves the Baltimore–Washington metropolitan area, centered on the District of Columbia.  The airport is named after John Foster Dulles, the 52nd Secretary of State who served under President Dwight D. Eisenhower.  The Dulles main terminal is a well-known landmark designed by Eero Saarinen.  Operated by the Metropolitan Washington Airports Authority, Dulles Airport occupies 13,000 acres (52.6 km) straddling the Loudoun-Fairfax line.  Most of the airport is in the unincorporated community of Dulles, in Loudoun County, with a small portion in the unincorporated community of Chantilly in Fairfax County.

Supporting paragraphs: Washington Dulles International Airport Gainesville Regional Airport
Answer: Washington Dulles International Airport