Final answer:
The World Trade Organization (WTO) is the stable medium for negotiating and arbitrating international trade disagreements among members.
Step-by-step explanation:
The stable medium for negotiating and observing international trade procedures and arbitrating trade disagreements among members is the World Trade Organization (WTO). The WTO establishes rules governing international trade and serves as a forum for negotiating trade deals and managing disputes that arise. As an organization that has been in existence since 1995, it provides a framework for trade agreements and a dispute resolution process which emphasizes the rule of law and contributes to the stability of the global economy.
In comparing with other options presented, although the International Monetary Fund (IMF) and the World Bank are involved in the global economy, they do not directly arbitrate trade disagreements like the WTO. Organizations like NAFTA and ASEAN, on the other hand, pertain to regional trade agreements rather than serving as a global platform for all nations.