こんにちは、学生の責任は何ですか？
it would be very thankful .

What???

Explanation:

attending classes on time and regularly. being prepared for classes with all necessary supplies. taking good care of school property. completing all homework assignments.

Explanation:

Is this the answer you needed, or?

united states government;

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."