The most difficult kind of frustration a person must deal with is probably
a. general frustration when everything seems to be going wrong
b. getting poor grade after working hard on school project
c. not being appreciated on the job
d. financial frustration

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; size, shape, color and status;