Question: Which of the Kapenguria Six was Kenya's first black head of government?

Context articles: Kapenguria Six
Fred Kubai
Jomo Kenyatta
Kung'u Karumba
Rawson Macharia
Heroes' Day (Kenya)
Kapenguria Museum
Stacy Adams (American football)
Fitz Remedios Santana de Souza
Nelson Mandela

The Kapenguria Six – Bildad Kaggia, Kung'u Karumba, Jomo Kenyatta, Fred Kubai, Paul Ngei, and Achieng' Oneko – were six leading Kenyan nationalists who were arrested in 1952, tried at Kapenguria in 1952–53, and imprisoned thereafter in Northern Kenya.
Fred Kubai (1917–June 1, 1996) was one of the Kapenguria Six, members of the Kenya African Union arrested in 1952, tried and imprisoned.
Jomo Kenyatta (  1897 – 22 August 1978) was a Kenyan anti-colonial activist and politician who governed Kenya as its Prime Minister from 1963 to 1964 and then as its first President from 1964 to 1978.
 He was the country's first black head of government and played a significant role in the transformation of Kenya from a colony of the British Empire into an independent republic.
 Ideologically an African nationalist and conservative, he led the Kenya African National Union (KANU) party from 1961 until his death.
Kung'u Karumba was a Kenyan nationalist and freedom-fighter.
 He was a member of the Kapenguria Six, along with Bildad Kaggia, Jomo Kenyatta, Fred Kubai, Paul Ngei, and Achieng Oneko.
Rawson Mbugua Macharia (b. 1911, d. 5 December 2008, aged 96) was the key prosecution witness at the trial of the Kapenguria Six, who included Jomo Kenyatta.
Mashujaa Day, also known as Heroes' Day ("mashujaa" is Swahili for "heroes"), is a national day in Kenya, which is observed on 20 October as a public holiday to collectively honour all those who contributed towards the struggle for Kenya's independence or positively contributed in the post independence Kenya.
 It was previously known as Kenyatta Day, which was celebrated to commemorate the detention in Kapenguria of freedom fighters Achieng' Oneko, Bildad Kaggia, Fred Kubai, Jomo Kenyatta, Kung'u Karumba and Paul Ngei, often referred to as the Kapenguria Six.
 However, following the promulgation of the Constitution of Kenya in August 2010, Kenyatta Day was renamed.
The Kapenguria Museum is a museum located in Kapenguria, Kenya.
 The museum is located inside the prison where prominent leaders of the Kenyan independence movement (the Kapenguria Six: Jomo Kenyatta, Kungu Karumba, Fred Kubai, Paul Ngei, Bildad Kaggia and Ramogi Achieng Oneko) were held and put on trial in 1952/3.
 The museum features galleries in the former cells of the prison, including displays on these leaders and the struggle against colonialism, and houses a memorial library in their honour.
Stacy Adams (born June 21, 1966) was the head football coach at Valparaiso University.
 He was the first black head football coach and the second documented black head coach at Valparaiso.
Fitzval Remedios Santana Neville de Souza (born 1929, Mumbai), often known as Dr. F. R. S.N. de Souza and Fitz De Souza, is a Kenyan lawyer and ex-politician of Indian origin, who was an important figure in the campaign for independence for Kenya, a member of the Kenyan parliament in the 1960s and Deputy Speaker for several years.
 He helped provide a legal defence for those accused of Mau Mau activities including the Kapenguria Six, and he was one of the people involved in the Lancaster House conferences held to draw up a constitutional framework for Kenyan independence.
Nelson Rolihlahla Mandela ( ; 18 July 1918 – 5 December 2013) was a South African anti-apartheid revolutionary, politician, and philanthropist, who served as President of South Africa from 1994 to 1999.
 He was the country's first black head of state and the first elected in a fully representative democratic election.
 His government focused on dismantling the legacy of apartheid by tackling institutionalised racism and fostering racial reconciliation.
 Ideologically an African nationalist and socialist, he served as President of the African National Congress (ANC) party from 1991 to 1997.