Concept:The UN organ that allows all member states to discuss and voluntarily cooperate on many issues is the General Assembly.Explanation:The General Assembly promotes international cooperation in political, economic, social, cultural, and humanitarian areas. Its recommendations are not legally binding, so cooperation among member states is voluntary. The Security Council deals with peace and security, ECOSOC handles only economic and social matters, and the International Court of Justice settles legal disputes.Answer:B. General Assembly