Question: Who was one of the best-known U.S. artists of the middle 20th century and was the subject of  a 2013 British documentary film directed by Eleanor Yule? 
Context: Albert Jay Nock (October 13, 1870 – August 19, 1945) was an American libertarian author, editor first of The Freeman and then The Nation, educational theorist, Georgist, and social critic of the early and middle 20th century.  He was an outspoken opponent of the New Deal, and served as a fundamental inspiration for the modern libertarian and Conservative movements, cited as an influence by William F. Buckley, Jr. He was one of the first Americans to self-identify as "libertarian".  His best-known books are "Memoirs of a Superfluous Man", and "Our Enemy, the State". Blinded is a film written and directed by Eleanor Yule.  In 2004 it won the Jury Award at the Celtic Film and Television Festival and it also won the Silver Screen award at the U.S. International Film and Video Festival.  It was nominated for the Raindance Award at the 2004 British Independent Film Awards. Michael Palin in Wyeth's World is a 2013 British documentary film directed by Eleanor Yule and featuring Michael Palin.  It is about the American painter Andrew Wyeth and the people who inspired his paintings. Andrew Newell Wyeth ( ; July 12, 1917 – January 16, 2009) was a visual artist, primarily a realist painter, working predominantly in a regionalist style.  He was one of the best-known U.S. artists of the middle 20th century. The Moo Man is a 2013 British documentary film, directed by Andy Heathcote, about an organic dairy farm in Sussex, England.  The film had its premiere at the 2013 Sundance Film Festival, where it competed in the World Cinema Documentary category. The Campground Historic District, also known as The Campground is a historic district in the city of Mobile, Alabama, United States.  Named for the Old Camp Ground, a military encampment that occupied the property during the American Civil War, this historically African American neighborhood was placed on the National Register of Historic Places on July 7, 2005.  It is roughly bounded by Martin Luther King Jr.  Avenue, Rylands Street, St. Stephens Road, and Ann Street.  The district covers 370 acre and contains 166 contributing buildings.  The houses range from shotgun houses to bungalows and date from the late 19th century to the middle 20th century. A coal hole is a hatch in the pavement (sidewalk, in US usage) above an underground coal bunker.  They are sometimes found outside houses that existed during the period when coal was widely used for domestic heating from the early 19th century to the middle 20th century.  In Britain they became largely obsolete within the major cities of the UK when the Clean Air Act forced a move towards oil and gas for home heating. Christina's World is a 1948 painting by American painter Andrew Wyeth, and one of the best-known American paintings of the middle 20th century.  It depicts a woman lying on the ground in a treeless, mostly tawny field, looking up at a gray house on the horizon; a barn and various other small outbuildings are adjacent to the house. Amazon Souls is a 2013 British documentary film directed, produced and presented by Sarah Begum.  The film examines the impact of modernity on the culture of the Huaorani tribe in the Ecuadorian Amazon Rainforest. Fire in the Night is a 2013 British documentary film about the Piper Alpha disaster directed by Anthony Wonke.  It won the Audience Award at the 2013 Edinburgh International Film Festival.  It was first shown on television on 9 July 2013 on BBC Two.
Answer: Andrew Wyeth