Question: Which family does the writer particularly discussed about their political activities in his book Dark Money?

full_context: Document 1: Citizen Koch: Citizen Koch is a 2013 documentary film directed by Tia Lessin and Carl Deal, concerning the political influence of American plutocrats following "Citizens United v. FEC" and of the eponymous Koch brothers, in particular. The film also focuses on the election of Wisconsin governor Scott Walker and his relationship with the Koch Brothers.
Document 2: Devil's Bargain: Devil's Bargain: Steve Bannon, Donald Trump, and the Storming of the Presidency is a book by "Bloomberg Businessweek" journalist Joshua Green about the partnership between Donald Trump and Steve Bannon that led to their 2016 political upset and the rise of the alt-right. Prior to writing the book, Green had worked as a journalist for "The Atlantic" and "Bloomberg", where he garnered experience reporting on conservatives. He had previously written a profile on Bannon in 2015, and interviewed Bannon for the book.
Document 3: Fred C. Koch: Fred Chase Koch ( ; September 23, 1900 – November 17, 1967) was an American chemical engineer and entrepreneur who founded the oil refinery firm that later became Koch Industries, a privately held company which, under the principal ownership and leadership of Koch's sons, Charles and David, is listed by "Forbes," as of 2015, as the second-largest privately held company in the United States.
Document 4: Jane Mayer: Jane Meredith Mayer (born 1955) is an American investigative journalist who has been a staff writer for "The New Yorker" since 1995. In recent years, she has written for that publication on money in politics, government prosecution of whistleblowers, the United States Predator drone program, Donald Trump's ghostwriter, and President Trump's financial backer, Robert Mercer. In 2016, Mayer's book "Dark Money", in which she investigated the history of the right-wing billionaire network centered around the Koch brothers, was published to critical acclaim.
Document 5: Radicals for Capitalism: Radicals for Capitalism: A Freewheeling History of the Modern American Libertarian Movement is a 2007 book about the history of libertarianism in the 20th century by American journalist and "Reason" senior editor Brian Doherty. He traces the evolution of the movement, as well as the life stories of Ayn Rand, Milton Friedman, Ludwig von Mises, F. A. Hayek, and Murray Rothbard, and details how they intertwined.
Document 6: Karl Denninger: Karl Denninger is an American technology businessman, finance blogger, and political activist, sometimes referred to as a founding member of the Tea Party movement.
Document 7: Dark Money (book): Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right (2016) is a non-fiction book written by the American investigative journalist Jane Mayer, about a network of extremely wealthy conservative libertarians, foremost among them Charles and David Koch, who have together funded an array of organizations that work in tandem to influence academic institutions, think tanks, the courts, statehouses, Congress, and the American presidency for their own benefit. Mayer particularly discusses the Koch family and their political activities, along with Richard Mellon Scaife and John M. Olin who funded the American Legislative Exchange Council (ALEC), and the DeVos and Coors families.
Document 8: Koch Brothers Exposed (film): Koch Brothers Exposed is a 2012 U.S. documentary, compiled by liberal political activist and filmmaker Robert Greenwald from a viral video campaign produced by Brave New Films, about the alleged political activities of the Koch brothers.
Document 9: Government Accountability Institute: The Government Accountability Institute (GAI) is a conservative nonprofit investigative research organization located in Tallahassee, Florida. GAI was founded in 2012 by Peter Schweizer and Stephen Bannon with funding from Robert Mercer and family. Schweizer serves as the group's president. The group is known for its involvement with the publication of the investigative books "Clinton Cash: The Untold Story of How and Why Foreign Governments and Businesses Helped Make Bill and Hillary Rich" and "Bush Bucks: How Public Service and Corporations Helped Make Jeb Rich".
Document 10: Cato Institute: The Cato Institute is an American libertarian think tank headquartered in Washington, D.C. It was founded as the Charles Koch Foundation in 1974 by Ed Crane, Murray Rothbard, and Charles Koch, chairman of the board and chief executive officer of the conglomerate Koch Industries. In July 1976, the name was changed to the Cato Institute.
Document 11: Clinton Cash: Clinton Cash: The Untold Story of How and Why Foreign Governments and Businesses Helped Make Bill and Hillary Rich is a 2015 "New York Times" bestselling book by Peter Schweizer in which he investigates donations made to the Clinton Foundation by foreign entities, paid speeches made by Bill and Hillary Clinton, and the state of the Clintons' finances since leaving the White House in 2001. It was published by Broadside Books, a division of HarperCollins. Research for the book was conducted by the Government Accountability Institute, a conservative nonprofit investigative research organization founded by Peter Schweizer and Steve Bannon. It has been adapted into both a film and a graphic novel.
Document 12: Political activities of the Koch brothers: The political activities of the Koch brothers include the financial and political influence of Charles G. and David H. Koch on United States politics. This influence is seen both directly and indirectly via various political and public policy organizations supported by the Koch brothers.
Document 13: Tea Party movement: The movement began following Barack Obama's first presidential inauguration (in January 2009) when his administration announced plans to give financial aid to bankrupt homeowners. A major force behind it was Americans for Prosperity (AFP), a conservative political advocacy group founded by businessmen and political activist David H. Koch. It is unclear exactly how much money is donated to AFP by David and his brother Charles Koch. Following a February 19, 2009 call by CNBC reporter Rick Santelli on the floor of the Chicago Mercantile Exchange for a "tea party," over fifty conservative activists agreed by conference call to coalesce against Obama's agenda and scheduled series of protests, including the 2009 Taxpayer March on Washington. Supporters of the movement subsequently have had a major impact on the internal politics of the Republican Party. Although the Tea Party is not a party in the classic sense of the word, some research suggests that members of the Tea Party Caucus vote like a significantly farther right third party in Congress.
Document 14: Dark money: In the politics of the United States, dark money are funds given to nonprofit organizations—and include 501(c)(4) (social welfare) 501(c)(5) (unions) and 501(c)(6) (trade association) groups—that can receive unlimited donations from corporations, individuals, and unions, and spend funds to influence elections, but are not required to disclose their donors. Dark money first entered politics with Buckley v. Valeo (1976) when the supreme court laid out Eight Magic Words that define the difference between electioneering and issue advocacy.
Document 15: Kenneth Vogel: Kenneth Vogel is an American journalist. He was the chief investigative reporter at "Politico", since its founding in 2007. In June 2017, he joined the Washington Bureau of "The New York Times" as a reporter covering conflict of interest issues, lobbying and money in politics. He is also the author of "Big Money: 2.5 Billion Dollars, One Suspicious Vehicle, and a Pimp–on the Trail of the Ultra-Rich Hijacking American Politics." Vogel's writing often focuses on money in politics. As part of his work, he focuses on political fundraising with particular emphasis on the political activities of the Koch brothers.
ground_truth: Koch family