What terms refers to the majority of americans that do not make their opinions known?

answer; for children with two myopic parents,the likelihood of becoming myopic is ) correlated with the number of hours spent playing sports each week;

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."