Answer:
In both Australia and Canada, citizens elect their representatives through their vote. This is because the two countries are parliamentary democracies. The head of government, the Prime Minister, is elected indirectly, because the Prime Minister is the leader of the party that obtains the most votes in Parliament.
In Cuba, citizens do not choose their leaders, because Cuba is not a democracy, but a one party communist republic where the head of government is appointed by the Cuban Communist Party, not by the people. This leader can stay in power for many years, even decades, as in the case of Fidel Castro.