Please answer the following question: Information:  - Sir John Alexander Macdonald (11 January 1815  6 June 1891) was the first Prime Minister of Canada (18671873, 18781891). The dominant figure of Canadian Confederation, he had a political career which spanned almost half a century. He drank heavily, and in 1873 was voted out during the Pacific Scandal, in which his party took bribes from businessmen seeking the contract to build the Pacific Railway. Macdonald's greatest achievements were building and guiding a successful national government for the new Dominion, using patronage to forge a strong Conservative Party, promoting the protective tariff of the National Policy, and building the transcontinental Canadian Pacific Railway. Economic growth was slow during his years in office, as Canada verged on stagnation; many residents migrated to the fast-growing United States. He fought to block provincial efforts to take power back from Ottawa. His most controversial move was to approve the execution of Métis leader Louis Riel for treason in 1885; it alienated many Francophones.  - Charles Joseph "Joe" Clark, (born June 5, 1939) is a Canadian statesman, businessman, writer, and politician who served as the 16th Prime Minister of Canada, from June 4, 1979, to March 3, 1980.  - Joseph Philippe Pierre Yves Elliott Trudeau (; October 18, 1919  September 28, 2000), better known as Pierre Trudeau or Pierre Elliott Trudeau, was a Canadian politician who served as the 15th Prime Minister of Canada from 19681979 and 19801984. He is the 3rd longest-serving Prime Minister in Canadian history (behind William Lyon Mackenzie King and John A. Macdonald), having served for 15 years, 164 days.  - The Conservative Party of Canada, colloquially known as the Tories, is a political party in Canada. It is positioned on the right of the Canadian political spectrum. The party's leader from 2004 to 2015 was Stephen Harper, who served as Prime Minister from 2006 to 2015.  - The Liberal Party of Canada, colloquially known as the Grits, is the oldest federal political party in Canada. The party espouses the principles of liberalism, and generally sits at the centre of the Canadian political spectrum. The Liberal Party is traditionally positioned to the left of the Conservative Party of Canada and to the right of the New Democratic Party (NDP).  - The Canadian federal election of 1979 was held on May 22 , 1979 to elect members of the Canadian House of Commons of the 31st Parliament of Canada . It resulted in the defeat of the Liberal Party of Canada after 11 years in power under Prime Minister Pierre Trudeau . Joe Clark led the Progressive Conservative Party to power , but with only a minority of seats in the House of Commons . The Liberals , however , did beat the Progressive Conservatives in the overall popular vote by more than 400,000 votes .  - William Lyon Mackenzie King (December 17, 1874  July 22, 1950) was the dominant Canadian political leader from the 1920s through the 1940s. He served as the tenth Prime Minister of Canada from 1921 to 1926, 1926 to 1930, and 1935 to 1948. He is best known for his leadership of Canada throughout the Second World War (19391945) when he mobilized Canadian money, supplies and volunteers to support Britain while boosting the economy and maintaining home front morale. A Liberal with 21 years and 154 days in office, he was the longest-serving prime minister in Canadian history. Trained in law and social work, he was keenly interested in the human condition (as a boy, his motto was "Help those that cannot help themselves"), and played a major role in laying the foundations of the Canadian welfare state.  - The New Democratic Party (NDP NPD) is a social-democratic political party in Canada. The leader of the federal wing of the NDP is Thomas Mulcair, who was elected in the 2012 leadership election, led the party through the 2015 federal election and then lost a party leadership review on April 10, 2016. Mulcair will remain as leader, until his replacement is chosen at a leadership election to be held in 2017.    Given the paragraphs above, decide what entity has the relation 'office contested' with 'prime minister of canada'.
A:
canadian federal election