Which factors cause an empire to rise to power? A. Thriving economy, stable leadership, and surplus food

B. Not enough money, stable leadership, and schools

C. Farming, barbarian invasions, and children going to work instead of school.

I would chose A, because that sounds more accurate

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."