Final answer:
Canada is described as a constitutional monarchy because it has a hereditary monarch who serves in a ceremonial capacity within the framework of the Constitution. This is a form of government where real political power lies with elected officials, and the role of the monarch is largely symbolic.
Step-by-step explanation:
To say Canada is a constitutional monarchy means that it has a hereditary Sovereign (Queen or King) who serves as the Head of State within the confines of a Constitution. The correct option from the given choices is B: Canada's Head of State is a hereditary Sovereign (Queen or King) who reigns in accordance with the Constitution.
In this form of government, the monarch has a largely ceremonial role with limited authority, while the elected Prime Minister and the Parliament exercise executive and legislative powers. The Canadian monarch appoints a Governor General as a representative, signifying the continued tradition and pageantry, although actual political power is vested in the elected democratic institutions.
A constitutional monarchy differs from an absolute monarchy in that the sovereign's powers are regulated by a constitution, unlike in an absolute monarchy where the monarch has unchecked power. Today's constitutional monarchies, like Canada's, evolved from absolute monarchies and now the monarch's role is largely symbolic and bound by constitutional laws.