Most of the north american tobacco crop was grown in the
appalachian foothills
tidewater region
piedmont region
spanish colonies

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."

permafrost layer, it exists beneath a layer of soil, rock or sediment.

answer; language that can promote racial stereotypes;

answer; well formed body;