Which river drains all of the land between the Rocky and Appalachian Mountains? A. The Columbia B. The Colorado C. The Rio Grande D. The Mississippi Please select the best answer from the choices provided A B C D.

D. The Mississippi
It is the best choice since the Mississippi River is the primary watercourse that drains the entire region between the Rocky and Appalachian Mountains. It originates in Minnesota and travels through the country's middle before emptying into the Gulf of Mexico in a southerly direction.

The vast drainage basin stretches from Montana in the west to Pennsylvania in the east and from the Canadian border to the Gulf of Mexico; the river drains portions of 31 states. Along its path, it receives water from many tributaries, including the Missouri, Ohio, and Arkansas rivers, among others, all of which help to contribute to its extensive drainage of the area between the Rocky and Appalachian Mountains.