Final answer:
The signing of the General Agreement on Tariffs and Trade (GATT) was the most significant move of the 1980s that fostered international cooperation among trading nations, reducing trade barriers and setting the stage for the World Trade Organization (WTO). Option A is corrcet.
Step-by-step explanation:
The most significant move of the 1980s that contributed toward international cooperation among trading nations was A. Signing of the General Agreement on Tariffs and Trade (GATT). The GATT was designed initially to prevent the resurgence of prewar-style trade barriers, lower trade barriers overall, and establish a framework for arbitrating international trade disputes. Although the GATT was formed in 1947, it continued to play a crucial role in promoting free trade and reducing tariffs and non-tariff barriers throughout the 1980s, which helped to increase the volume of international trade.
Despite economic recessions and the rise of protectionist policies in the 1970s and 1980s, the GATT rounds continued to foster multinational discussions to reduce trade restrictions. The GATT's impact was significant up until its replacement by the World Trade Organization (WTO) in 1995, which carried forward its legacy and principles. The GATT's relevance is exemplified by the engagement of developing countries in the Uruguay Round and the global reduction in trade barriers during its existence.