The correct answer is the western physiographic region. This region is the largest physiographic division of Ethiopia. It is characterized by highlands, plateaus, and mountains, including the Ethiopian Highlands, which are the largest continuous mountain ranges in Africa. The region is known for its diverse landscapes, including deep canyons, rugged cliffs, and fertile valleys. It is also home to many rivers, including the Blue Nile, which originates in the highlands. The western physiographic region plays a significant role in Ethiopia's geography, climate, and natural resources.