Who is considered the formal head of state in Canada?

In Canada, the formal head of state is represented by the monarch, who, at the time referenced in your answer, was Queen Elizabeth II. The monarch's role is largely ceremonial, and they fulfill various constitutional and symbolic duties, which are carried out in Canada through the Governor General. While the Governor General acts on behalf of the Queen and represents her interests in Canada, the ultimate title of head of state rests with the monarch. This distinction is important within the context of Canada's parliamentary system, where the functioning of government and day-to-day political power resides with elected officials, but the monarch remains the official head of state in principle.

The Prime Minister serves as the head of government and is responsible for running the country and making policy decisions, while the Chief Justice is the head of the judiciary. Though these roles are critical to the functioning of government, they do not hold the formal title of head of state as vested in the monarchy. Thus, the answer identifying Queen Elizabeth II aligns with the constitutional framework of Canada, where she is recognized as the formal head of state.