Which of the following is NOT one of the three categories of landform regions of Canada?

The three main categories of landform regions in Canada are Highlands, Lowlands, and the Canadian Shield. Each of these categories encompasses distinct geographical features and landscapes.

Highlands refer to areas of elevated terrain, such as mountains and plateaus, where various geological processes have shaped the landscape over time. Lowlands are flatter areas that may include plains or valleys, characterized by their lower elevation compared to adjacent highland regions. The Canadian Shield is a vast region made primarily of ancient crystalline rocks, which underlies much of eastern and northern Canada.

While plateaus are indeed a type of landform found within these broader categories, they are not a standalone category representing a separate landform region in Canada. Instead, plateaus can be considered specific examples of highland areas. Thus, recognizing that plateaus do not stand as one of the three main landform categories clarifies why this choice does not belong among the options presented.