As a president, if you disagree with a bill, you should...
A. change it
B. veto it
C. cancel it
D. sign it

the 2nd option is the answer

answer; /// the correct answer is (belongingness needs; good luck

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."