Which U.S. state includes part of the main Continental Divide?

Montana is indeed the U.S. state that includes a significant portion of the Continental Divide, which is a natural boundary that separates the watersheds that drain into the Pacific Ocean from those that drain into the Atlantic Ocean. The Continental Divide runs along the Rocky Mountains and is a key feature in the geography of the western United States. Within Montana, the Divide traverses through several mountain ranges, including parts of Glacier National Park, which is known for its stunning landscapes and biodiversity.

The locations of the other choices do not align with the Continental Divide. Maine is located in the northeastern part of the country and is characterized by different geographical features, primarily coastal and forested areas. Washington, while having mountainous terrain, does not feature the Continental Divide as prominently as Montana, and the state's major divides are oriented differently. South Carolina, located in the southeastern U.S., has a climate and geography influenced more by coastal plains and low hills, not by the mountainous divides that characterize the western states. Therefore, Montana stands out as the clear choice for being part of the main Continental Divide.