Question: What is the official language of the host city for the Commonwealth Heads of Government Meeting in 1979?

Context articles: Commonwealth Heads of Government Meeting
Commonwealth Heads of Government Meeting 1971
Singapore Declaration
Commonwealth Heads of Government Meeting 2009
Commonwealth Heads of Government Meeting 2015
Commonwealth Heads of Government Meeting 1977
Commonwealth Heads of Government Meeting 2013
Lusaka
Commonwealth Heads of Government Meeting 1979
Commonwealth Heads of Government Meeting 1986

The Commonwealth Heads of Government Meeting (CHOGM; or ) is a biennial summit meeting of the heads of government from all Commonwealth nations.
 Every two years the meeting is held in a different member state and is chaired by that nation's respective Prime Minister or President who becomes the Commonwealth Chair-in-Office until the next meeting.
 Queen Elizabeth II, who is the Head of the Commonwealth, attended every CHOGM beginning with Ottawa in 1973 until Perth in 2011, although her formal participation only began in 1997.
 However, she was represented by the Prince of Wales at the 2013 meeting as the 87-year-old monarch was curtailing her overseas travel.
 The Queen continues to attend CHOGMs held in Europe and was present at the 2015 summit in Malta and is expected to attend the 2018 CHOGM which is to be held in London.
The Commonwealth Heads of Government Meeting 1971 was the first Meeting of the Heads of Government of the Commonwealth of Nations (formerly named the British Commonwealth).
 It was held in Singapore, between 14 January 1971 and 22 January 1971, and was hosted by that country's Prime Minister, Lee Kuan Yew.
The Singapore Declaration of Commonwealth Principles was a declaration issued by the assembled Heads of Government of the Commonwealth of Nations, setting out the core political volunteering values that would form the main part of the Commonwealth's membership criteria.
 The Declaration was issued in Singapore on 22 January 1971 at the conclusion of the first Commonwealth Heads of Government Meeting (CHOGM).
 Along with the Harare Declaration, issued in 1991, it is considered one of the two most important documents to the Commonwealth's uncodified constitution.
The Commonwealth Heads of Government Meeting 2009 was the twenty-first Meeting of the Heads of Government of the Commonwealth of Nations.
 It was held in Port of Spain, Trinidad and Tobago, between 27 and 29 November 2009, and was hosted by that country's Prime Minister, Patrick Manning.
The Commonwealth Heads of Government Meeting 2015, also known as CHOGM 2015 was the 24th meeting of the heads of government of the Commonwealth of Nations.
 It was held in Malta from 27 to 29 November.
 Sri Lankan President Maithripala Sirisena handed the position of Commonwealth Chair-in-Office to Maltese prime minister Joseph Muscat at the meeting.
The Commonwealth Heads of Government Meeting 1977 was the fourth Meeting of the Heads of Government of the Commonwealth of Nations.
 It was held in London, the United Kingdom, between 8 June 1977 and 15 June 1977, and was hosted by that country's Prime Minister, James Callaghan.
 President Idi Amin of Uganda did not attend, and on the eve of the meeting President James Mancham of the Seychelles was overthrown and the country was not represented.
The 23rd Commonwealth Heads of Government Meeting (CHOGM; ) was held in Colombo, Sri Lanka, from 15 to 17 November 2013.
 Commonwealth leaders agreed on Sri Lanka as the 2013 host for the meeting when they met in Port of Spain, Trinidad and Tobago, in 2009.
 Sri Lanka, which was originally slated to host the summit in 2011, was accused of committing atrocities during the Sri Lankan civil war and the summit was instead held in Perth, Australia; Colombo was given the 2013 summit instead.
 The leaders of Canada, Mauritius, and India boycotted the summit, citing alleged human rights violations by Sri Lanka against its Tamil minority.
 Protests were also banned during the summit.
 President Mahinda Rajapaksa summarised the summit's events as: "Issues covered in the communique include development, political values, global threats, challenges and Commonwealth cooperation."
 However, the meeting was overshadowed by controversy over Sri Lanka's human rights record and the alleged war crimes during the final stages of the civil war.
 This was the first time in 40 years that the Head of the Commonwealth, Queen Elizabeth II, was not present at the CHOGM.
Lusaka is the capital and largest city of Zambia.
 One of the fastest developing cities in southern Africa, Lusaka is in the southern part of the central plateau at an elevation of about 1279 m .
 s of 2010 , the city's population was about 1.7 million, while the urban population is 2.4 million.
 Lusaka is the centre of both commerce and government in Zambia and connects to the country's four main highways heading north, south, east and west.
 English is the official language of the city, but Nyanja and Bemba are also common.
The Commonwealth Heads of Government Meeting 1979 was the fifth Meeting of the Heads of Government of the Commonwealth of Nations.
 39 countries attended the meeting.
 It was held in Lusaka, Zambia, between 1 August 1979 and 7 August 1979, and was hosted by that country's President, Kenneth Kaunda.
The Commonwealth Heads of Government Meeting 1986 was the ninth Meeting of the Heads of Government of the Commonwealth of Nations.
 It was held in London, the United Kingdom, between 3 August 1986 and 5 August 1986, and was hosted by that country's Prime Minister, Margaret Thatcher.
 This was a special meeting held in between the biennial CHOGMs in order to consider the recommendations of the Commonwealth Eminent Persons Group regarding economic sanctions against South Africa due to its policies of apartheid.
 British prime minister Margaret Thatcher's refusal to support mandatory sanctions resulted in an acrimonious meeting and almost led to a split in the Commonwealth.