Question: Kenneth Ross screenwrote "The Day of the Jackal" based on which author's 1971 novel?
Context: Kenneth Ross Stevenson (born October 1, 1942) is a former politician in Ontario, Canada.  He served in the Legislative Assembly of Ontario from 1981 to 1987, and was briefly a cabinet minister in the government of Frank Miller.  He later served in the House of Commons of Canada from 1988 to 1993.  Stevenson was a member of the Progressive Conservative Party. Black Sunday is a 1977 American thriller film directed by John Frankenheimer, based on Thomas Harris' novel of the same name.  The film was produced by Robert Evans, and stars Robert Shaw, Bruce Dern and Marthe Keller.  It was nominated for the Edgar Allan Poe Award for Best Motion Picture in 1978.  The screenplay was by Ernest Lehman, Kenneth Ross and Ivan Moffat.  Ross had previously written the screenplay for "The Day of the Jackal", a similar plot-driven political thriller. Kenneth Ross is the Scottish-American screenwriter of the films "The Day of the Jackal" and "The Odessa File". Kenneth Ross MacKenzie (June 15, 1912 – July 4, 2002) together with Dale R. Corson and Emilio Segrè, synthesized the element astatine, in 1940.  MacKenzie received his PhD under Ernest Lawrence at Lawrence Livermore National Laboratory.  Lawrence, MacKenzie, and their colleagues devised the first cyclotron.  He was a professor of physics at UCLA, where he and Reg Richardson built UCLA's first cyclotron and later a bevatron.  MacKenzie devised MacKenzie buckets which are plasma sources created by lining vacuum chamber walls with permanent magnets of alternating polarity to suppress plasma electron losses, that are widely used to this day.  He later traveled around the world, helping to troubleshoot various country's cyclotron problems.  Later in life, he studied plasma physics and dark matter. Dr. Kenneth Ross "Ken" Henry {'1': ", '2': ", '3': ", '4': "} (born 27 November 1957 in Taree, New South Wales) is an Australian economist and public servant.  He served as the Secretary of the Department of the Treasury from 2001 to 2011, first appointed by Liberal Party Treasurer Peter Costello in April 2001, reappointed by Costello in 2006, and retained by the Rudd government.  He chaired the Australia's Future Tax System Review, informally known as the Henry Tax Review, that was published in 2010.  He retired in March 2011, and on 1 June 2011 was appointed as Special Advisor to the Prime Minister.  He chaired the committee which produced a White Paper on "Australia in the Asian Century", released in mid-2012.  Henry is currently the Chairman of the National Australia Bank, the Australian Securities Exchange (ASX) and Sir Roland Wilson Foundation at the Australian National University. The Jackal is a fictional character, the villain of the novel "The Day of the Jackal" by Frederick Forsyth.  He is an assassin who is contracted by the OAS French terrorist group of the early 1960s, to kill Charles de Gaulle, the President of France.  The book was published on 7 June 1971, in the year following de Gaulle's death, and became an instant bestseller.  In the original 1973 film adaptation, he is portrayed by Edward Fox.  A revised version of the character was portrayed by Bruce Willis in the 1997 remake, "The Jackal", having a divergent storyline and set in the U.S., with the First Lady as target of the assassination. The Ross and Sutherland Constabulary was a Police Force in Scotland that existed between 16 May 1963 and 16 May 1975.  Kenneth Ross, BL was the Chief Constable of the force for its entire existence. Kenneth Ross Toole (August 8, 1920 - August 13, 1981) was an American historian, author, and educator who specialized in the history of Montana.  Perhaps the best-known and most influential of the state's twentieth-century historians, Toole served as director of the state's historical society, authored several noted volumes of state history and social commentary, and was a popular professor at the University of Montana for 16 years.  He supported environmental protection for Montana's resources, and voiced strong support for labor unions and farmers over big business, especially targeting the railroad and mining industries.  These views frequently came into conflict with those of the Anaconda Copper Company and some Montana politicians, most notably Governor J. Hugo Aronson (served 1953-1961).  Toole's views on the role of corporate dominance in Montana history were often controversial, and have been hotly debated by historians. Kenneth Ross Hunter FRCP (31 May 1939 – 26 April 2013) was a Scottish consultant physician who specialised in diabetes. The Day of the Jackal is a 1973 Anglo-French political thriller film directed by Fred Zinnemann and starring Edward Fox and Michel Lonsdale.  Based on the 1971 novel "The Day of the Jackal" by Frederick Forsyth, the film is about a professional assassin known only as the "Jackal" who is hired to assassinate French president Charles de Gaulle in the summer of 1963.
Answer: Frederick Forsyth