Question: Bernard Vonnegut I was grandfather to which author who wrote "Slaughterhouse-Five"?

Context paragraphs:
Clemens Vonnegut: Clemens Vonnegut Sr. (November 20, 1824 – December 13, 1906) was a German emigrant to the United States and successful businessman.  He was the patriarch of the prominent German-American Vonnegut clan (later Schnull-Vonnegut) of Indiana – he was the father and grandfather of architects Bernard Vonnegut I and Kurt Vonnegut Sr., respectively, and great-grandfather of scientist Bernard Vonnegut and author Kurt Vonnegut Jr.

A Man Without a Country: A Man Without a Country (subtitle: "A Memoir Of Life In George W Bush's America") is an essay collection published in 2005 by the author Kurt Vonnegut.  The extremely short essays that make up this book deal with topics ranging from the importance of humor, to problems with modern technology, to Vonnegut's opinions on the differences between men and women.  Most prevalent in the text, however, are those essays that elucidate Vonnegut's opinions on politics, and the issues in modern American society, often from a decidedly humanistic perspective.  In January 2007, Vonnegut indicated that he intended this to be his final work, a statement that proved to be correct with his death in April 2007.  Later published works of Vonnegut's were all published posthumously, and consisted almost entirely of previously unpublished material from early in his career.

Bernard Vonnegut: Bernard Vonnegut (August 29, 1914 – April 25, 1997) was an American atmospheric scientist credited with discovering that silver iodide could be used effectively in cloud seeding to produce snow and rain.  He was the older brother of American novelist Kurt Vonnegut.

Stephen Geller: Stephen Geller (b. Los Angeles, California) is an American screenwriter and novelist.  He wrote the screenplay for the film adaptation of Kurt Vonnegut's novel "Slaughterhouse-Five", and has worked in the film industry in Hollywood and Europe.  Geller recently directed his own independent feature, "Mother's Little Helpers".

Billy Pilgrim: Billy Pilgrim is a fictional character and protagonist of Kurt Vonnegut's 1969 novel "Slaughterhouse-Five", who has appeared in adaptations of the novel for film and the stage.  Billy Pilgrim was based on Vonnegut's comrade-in-arms Edward R. Crone, Jr.

Kurt Vonnegut: Kurt Vonnegut Jr. ( ; November 11, 1922April 11, 2007) was an American writer.  In a career spanning over 50 years, Vonnegut published 14 novels, three short story collections, five plays, and five works of non-fiction.  He is most famous for his darkly satirical, best-selling novel "Slaughterhouse-Five" (1969).

Yon Yonson: "Yon Yonson" is an infinitely recursive poem, nursery rhyme or song, perhaps best known from the novel "Slaughterhouse-Five" by Kurt Vonnegut, although Vonnegut did not create it.

Bernard Vonnegut I: Bernard Vonnegut I, WAA, FAIA, (August 8, 1855 – August 7, 1908) was an American lecturer and architect active in late-nineteenth and early-twentieth-century Indiana.  He was a co-founder of the locally renowned Indianapolis architectural firm of Vonnegut and Bohn, and was active in a range of residential, religious, institutional, civic, and commercial commissions.  He is the namesake and grandfather of scientist Bernard Vonnegut, father of the architect Kurt Vonnegut Sr., and grandfather of author Kurt Vonnegut.

Slaughterhouse-Five: Slaughterhouse-Five, or The Children's Crusade: A Duty-Dance with Death (1969) is a satirical novel by Kurt Vonnegut about the World War II experiences and journeys through time of Billy Pilgrim, from his time as an American soldier and chaplain's assistant, to postwar and early years.  It is generally recognized as Vonnegut's most influential and popular work.  A central event is Pilgrim's surviving the Allies' firebombing of Dresden as a prisoner-of-war.  This was an event in Vonnegut's own life, and the novel is considered semi-autobiographical.

Kurt Vonnegut Sr.: Kurt Vonnegut Sr. (November 24, 1884 – October 1, 1957) was an American architect and architectural lecturer active in early- to mid-twentieth-century Indianapolis, Indiana.  A member of the American Institute of Architects, he was partner in the firms of Vonnegut & Bohn, Vonnegut, Bohn & Mueller, and Vonnegut, Wright, and Yeager.  He designed several churches, banks, and became the inhouse architect for Indiana Bell and Hooks Drug stores (prior to World War II), practicing extensively in the Art Deco style.  He was the father of chemist Bernard Vonnegut and author Kurt Vonnegut Jr.

Supporting paragraphs: Bernard Vonnegut I Kurt Vonnegut
Answer: Kurt Vonnegut