When did john A Macdonald stop being prime minister?

Sir John A. Macdonald became the Prime Minister again after Alexander Mackenzie on 1878 October 17.

OR

Sir John A. Macdonald was elected to the position of Prime Minister on elections on

• 1872 October 12 (2nd parliament)
• 1878 September 17 (4th parliament)
• 1882 June 20 (5th parliament)
• 1887 February 22 (6th parliament)
• 1891 March 5 (7th parliament)