Scientists think this region may have once been a large sea plains

The correct answer is Interior Plains.

Explanation:

This region known as Interior Plains is a geographical region located close to the craton (the stable portion of the continental crust) of Central America. This region is delimited by the Gulf Coast region and the Arctic Ocean along the east flank of the Rocky Mountains.

your answer should be c, it seems to be the only one that makes sense. mark me branliest : )

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer