What are its essential components, and how are they related to one another?

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."

chavez's example shows that nonviolent protest can work well. it shows that one nonviolent man can stop a mob, which proves chavez's point and persuades people to protest nonviolently.

okay what's the question?