The correct answer is C) the Atlantic Ocean to the Pacific Ocean.
The phrase transcontinental nation refers to the United States spanning from the Atlantic Ocean to the Pacific Ocean.
The United States has a large territorial extension that has seas in the West and the East. When the term "transcontinental" is applied, this means that the territory expands from one point on the coast of an ocean to the other extreme. In this case, The phrase transcontinental nation refers to the United States spanning from the Atlantic Ocean to the Pacific Ocean. This was also the case when naming the Transcontinental Railroad that connected the East coast of the United States with the West Coast in the Pacific Ocean.