Explain the organs of UNO​

The United Nations (UN) has six main organs. Five of them — the General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council and the Secretariat — are based at UN Headquarters in New York. ... The United Nations is neither a supra-State nor a government of governments.

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."