Question: Ruth Williams Khama, Lady Khama, was the wife of the first President of Botswana, in office from 1966 to 1980, his name? 

full_context: Document 1: First Lady of Botswana: The First Lady of the Republic of Botswana is the title used by the wife of the President of Botswana. Botswana's inaugural First Lady was Lady Ruth Williams Khama, the English-born wife of the country's inaugural President, Seretse Khama.
Document 2: Seretse Khama: Sir Seretse Goitsebeng Maphiri Khama, GCB, KBE (1 July 1921 – 13 July 1980) was the first President of Botswana, in office from 1966 to 1980.
Document 3: Bechuanaland general election, 1965: General elections were held in the Bechuanaland Protectorate on 1 March 1965, the country's first election under universal suffrage. The result was a landslide victory for the Bechuanaland Democratic Party, with Seretse Khama becoming Prime Minister. Following the elections, the country became independent as Botswana on 30 September 1966, at which point Khama became President. Voter turnout was 74.55% of the 188,950 registered voters.
Document 4: Dr Kenneth Kaunda District Municipality: Dr Kenneth Kaunda District Municipality (formerly Southern District Municipality) is one of the 4 districts of North West province of South Africa. The seat of Kaunda District is Klerksdorp. The majority of its 742 821 people speak Setswana (2016 Census). The majority of its people live in the City of Matlosana Municipality. The district code is DC40. The district was formerly known as the Southern District Municipality. It is named after Kenneth Kaunda, the first President of Zambia. The Chief Director of Cutural Affairs is Taz Liwane.
Document 5: Michael Sata: Michael Chilufya Sata (6 July 1937 – 28 October 2014) was a Zambian politician who was the fifth President of Zambia, from 23 September 2011 until his death on 28 October 2014. A social democrat, he led the Patriotic Front (PF), a major political party in Zambia. Under President Frederick Chiluba, Sata was a minister during the 1990s as part of the Movement for Multiparty Democracy (MMD) government; he went into opposition in 2001, forming the PF. As an opposition leader, Sata – popularly known as "King Cobra" – emerged as the leading opposition presidential contender and rival to President Levy Mwanawasa in the 2006 presidential election, but was defeated. Following Mwanawasa's death, Sata ran again and lost to President Rupiah Banda in 2008.
Document 6: Sir Seretse Khama International Airport: Sir Seretse Khama International Airport (IATA: GBE, ICAO: FBSK) , located 15 km north of Gaborone, is the main international airport of the capital city of Botswana. The airport is named after Sir Seretse Khama, the first president of Botswana. It was opened in 1984 and offers limited capacity to handle regional and (especially)international traffic. Nonetheless, it has the largest passenger movement in the country.
Document 7: Semane Setlhoko Khama: Semane Setlhoko Khama (1881-1937) was the mohumagadi (queen or queen mother) of the BaNgwato of the Bechuanaland Protectorate, now Botswana, and the fourth and final wife of king Khama III. She married him in 1900. She had five children, three of whom died young, and one of whom, Tshekedi, was regent of the BaNgwato from 1925 to 1950. She was a Christian and a member of the Woman's Christian Temperance Union, to which in 1933 she brought in the highest number of recruits. She also created a branch of the WCTU called the Women's Regiment of Beer. She preached to women and men in the central village meeting place, which until then had been a male political place. She increased women's activism and membership in the church, and conducted church-related classes and taught women how to conduct their own classes. She also promoted modern medicine and midwifery.
Document 8: Tshekedi Khama II: Tshekedi Stanford Khama (born 9 June 1958) is a Botswana Member of Parliament from Serowe North-West. He is a member of the Botswana Democratic Party (BDP). He is also the brother of the current President of Botswana, Ian Khama, and one of the three sons of the first President of Botswana, Seretse Khama and Ruth Williams Khama.
Document 9: List of heads of government of Botswana: The office of Prime Minister of Botswana existed from 3 March 1965 to 30 September 1966, during which time it was held by one individual, Seretse Khama, who later served as President from 1966 until his death on 13 July 1980.
Document 10: Pilikwe: Pilikwe is a rural village in Central District in Botswana. It was founded by Kgosi Tshekedi Khama of Bangwato. The current chief of the village is Kgosi Gasebalwe Seretse. The village is also known by the native name 'Rametsana'.
Document 11: A United Kingdom: A United Kingdom is a 2016 British biographical romantic drama film directed by Amma Asante and written by Guy Hibbert, based on the true-life romance between Sir Seretse Khama and his wife Ruth Williams Khama. David Oyelowo and Rosamund Pike portray Seretse and Ruth, respectively.
Document 12: Mma-Besi: Mma-Besi or Mabisa (1846-1889) was the mohumagadi (queen or queen mother) of the BaNgwato of the Bechuanaland Protectorate, now Botswana, and the first wife of king Khama III. She was baptized Elizabeta in 1862, taking the name in honor of Elizabeth Moffat, daughter of Robert Moffat. She was married that same year in what was the first Christian marriage held in Shoshong. Her first child, a daughter, was called Besi, and so she became Mma-Besi due to a tradition of taking the name "mother of" one's firstborn. Her one son who lived, Sekgoma, became king when Khama III died in 1923 but died himself soon after. She herself died at age 44, likely of malaria due to Khama III moving the capital to the Tswapong Hills, an unhealthy place.
Document 13: Tshekedi Khama: Tshekedi Khama (17 September 1905, Serowe - 10 June 1959, London) was the regent of the Bamangwato tribe in 1926 after the death of Sekgoma II.
Document 14: Parliament of Botswana: The Parliament of Botswana consists of the President and the National Assembly. In contrast to other Parliamentary systems, the Parliament elects the President directly (instead of having both a ceremonial President and a Prime Minister who has real authority as head of government) for a set five-year term of office. There are no term limits. The President is both head of State and of Government in Botswana's parliamentary republican system. The current President of Botswana is Ian Khama, who assumed the Presidency on 1 April 2008 and won a full five-year term in the postceding Botswana General elections, which were held on 16 October 2009 and returned his Botswana Democratic Party with a majority of 35 (total of 45) seats in the 61 seat Parliament.
Document 15: Ruth Williams Khama: Ruth Williams Khama, Lady Khama (9 December 1923 – 22 May 2002) was the wife of Botswana's first president Sir Seretse Khama, the Paramount Chief of its Bamangwato tribe. She served as the inaugural First Lady of Botswana from 1966 to 1980.
ground_truth: Seretse Goitsebeng Maphiri Khama