Roughly where in the USA is the area called Tornado Alley?

Question

Which of these is a natural area of roughly 16 square km (6.2 squ miles), which is 5 km (3.1 miles) west of Tuktoyaktuk, Canada, in a coastal region of the Arctic Ocean, which contains approximately 1,350 Arctic ice dome hills?

Answer 1

North-South: Dakota through Kansas and Oklahoma to Texas
The region between the Rockies and the Appalachians is where warm, moist air from the Gulf of Mexico meets cold, dry air from the Rocky Mountains and Canada, and produces the strongest and most frequent tornadoes.