How could the failures of the League of Nations have led to the beginning of World War II in 1939?

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; does not include a reference to the audience;

answer; intentional; outrageous;

answer; answer; marginal cost;