Question: NASA Astronaut Group 5 includes the last living pilot of which North American test flight program?
Context: Robert Franklyn "Bob" Overmyer (July 14, 1936 – March 22, 1996), (Col, USMC), was an American test pilot, naval aviator, aeronautical engineer, physicist, United States Marine Corps officer, and USAF/NASA astronaut.  He was born in Lorain, Ohio, but considered Westlake, Ohio his hometown.  Overmyer was selected by the United States Air Force as an astronaut for its Manned Orbiting Laboratory in 1966.  Upon cancellation of this program in 1969, he became a NASA astronaut and served support crew duties for the Skylab program and Apollo-Soyuz Test Project.  In 1976, he was assigned to the Space Shuttle program, and flew as pilot on STS-5 in 1982, and as commander on STS-51-B in 1985.  He was selected as a lead investigator into the Space Shuttle "Challenger" disaster, and retired from NASA in 1986.  Ten years later, Overmyer died in Duluth, Minnesota while testing the Cirrus VK-30 composite homebuilt aircraft. Charles Gordon Fullerton (October 11, 1936 – August 21, 2013) was a United States Air Force colonel, a USAF and NASA astronaut, and a research pilot at NASA's Dryden Flight Research Facility, Edwards, California.  His assignments included a variety of flight research and support activities piloting NASA's B-52 launch aircraft, the Boeing 747 Shuttle Carrier Aircraft (SCA), and other multi-engine and high performance aircraft.  Fullerton, who logged more than 380 hours in space flight, was a NASA astronaut from September 1969 until November 1986 when he joined the research pilot office at Dryden.  In July 1988, he completed a 30-year career with the U.S. Air Force and retired as a colonel.  He continued in his position of NASA research pilot as a civilian.  Fullerton and his wife and their two children lived in Lancaster, California. Michael Scott Hopkins (born December 28, 1968) is a Colonel in the U.S. Air Force, and a current NASA astronaut.  Hopkins was selected in June 2009 as a member of the NASA Astronaut Group 20.  He made his first spaceflight as a Flight Engineer on Soyuz TMA-10M/Expedition 37/Expedition 38, from September 2013 until March 2014.  He was the first member of his astronaut class to fly in space. Gregory Reid Wiseman (born November 11, 1975) is an American astronaut, engineer, and naval aviator.  Wiseman was selected in June 2009 as a member of the NASA Astronaut Group 20 and qualified as an astronaut in 2011.  Wiseman took part in his first spaceflight as part of the crew of Expedition 40/41, which launched to the International Space Station on May 28, 2014, and returned on November 10, 2014.  Before joining NASA, Wiseman was a Naval Aviator and test pilot. Alan LaVern Bean (born March 15, 1932), (CAPT, USN, Ret.) , is an American former naval officer and Naval Aviator, aeronautical engineer, test pilot, and NASA astronaut; he was the fourth person to walk on the Moon.  He was selected to become an astronaut by NASA in 1963 as part of Astronaut Group 3.  He made his first flight into space aboard Apollo 12, the second manned mission to land on the Moon, at the age of thirty-seven years in November 1969.  He made his second and final flight into space on the Skylab 3 mission in 1973, the second manned mission to the Skylab space station.  After retiring from the United States Navy in 1975 and NASA in 1981, he pursued his interest in painting, depicting various space-related scenes and documenting his own experiences in space as well as that of his fellow Apollo program astronauts. Jack David Fischer (born January 23, 1974) is an American engineer, test pilot and a NASA astronaut.  Fischer was selected in June 2009 as a member of the NASA Astronaut Group 20 and qualified as an astronaut in 2011.  He made his first spaceflight in April 2017, as a flight engineer for Expedition 51/52 on the International Space Station. Lee Joseph "Bru" Archambault (born August 25, 1960) is an American test pilot and former NASA astronaut.  He has logged over 4,250 flight hours in more than 30 different aircraft.  Archambault is married with three children.  His hobbies include bicycling, weightlifting, and playing ice hockey.  Archambault has received numerous awards and honors throughout his life.  He has also flown two Space Shuttle missions, as pilot of STS-117 in 2007 and as commander of STS-119 in 2009.  Archambault left NASA in 2013 after a 15-year career with the agency in order to become a test pilot for Sierra Nevada Corporation on their Dream Chaser orbital spaceplane project. Joe Henry Engle (born August 26, 1932), (Maj Gen, USAF, Ret.) , is an American pilot who served in the United States Air Force, test pilot for the North American X-15 program, aeronautical engineer, and a former NASA astronaut.  As of 2017, he is the last living pilot of the X-15 program. Clifton Curtis "C.C." Williams Jr. (September 26, 1932 – October 5, 1967), (Major, USMC), was an American naval aviator, test pilot, mechanical engineer, Major in the United States Marine Corps, and NASA astronaut, who was killed in a plane crash; he had never been to space.  The crash was caused by a mechanical failure in a NASA T-38 jet trainer, which he was piloting to visit his parents in Mobile, Alabama.  The failure caused the flight controls to stop responding, and although he activated the ejection seat, it did not save him.  He was the fourth astronaut from NASA's Astronaut Group 3 to have died, the first two (Bassett and Freeman) having been killed in separate T-38 flights and (Chaffee) in the Apollo 1 fire earlier that year.  The aircraft crashed in Florida near Tallahassee within an hour of departing Patrick AFB. NASA's Astronaut Group 5 was selected by NASA in April 1966.  Of the six Lunar Module Pilots that walked on the Moon, three came from Group 5.  The group as a whole is roughly split between the half who flew to the Moon (nine in all) and the other half who flew Skylab and Shuttle, providing the core of Shuttle Commanders early in that program.  This group is also distinctive in being the only time when NASA hired a person into the astronaut corps who had already earned astronaut wings, X-15 pilot Joe Engle.  John Young labelled the group the "Original Nineteen" in parody of the original seven Mercury astronauts.
Answer: X-15