The interior plains of the united states include the and the

answer; in the united states the plains include the great plains of the west and the tail grass prairie to the south of the great lakes extending east to the appalachian plateau

d. new methods of assembly are introduced.

explanation:

this allows for the goods to be made on a larger scale. not faster because now it is shown to be made better, hence the greater productivity in the question. it is calling for something new to be introduced.