Which of the following was a major factor in the decline of the Byzantine empire? A. the decision to divide the Roman empire in two B. the dispute between the pope and the patriarch of Constantinople C. repeated attacks by Muslim invaders D. the conquests of Justinian in the west

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."

answer; nonpartisan election;