Ben works as an accountant at the headquarters of a fast-food chain. his boss regularly insults him with such comments as, "you are the dumbest accountant i ever met," and "you could easily be replaced with quicken software." ben will most likely experience

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."