Final answer:
Increased trade between Canada and the USA was significantly boosted by the signing of the North American Free Trade Agreement (NAFTA), which eliminated many trade barriers and established the world's largest trading bloc.
Step-by-step explanation:
The catalyst for significantly increased trade between Canada and the USA was C. The signing of the North American Free Trade Agreement (NAFTA). NAFTA, established in 1994, was a groundbreaking economic policy that joined Canada, the United States, and Mexico in an agreement that eliminated many trade barriers such as tariffs and quotas, paving the way for free trade and a more integrated continental market. The agreement provided stable and secure access to the markets of the member countries, leading to the expansion of trade sectors such as agriculture, automotive, and textiles, as well as services like finance, transportation, and telecommunications.
NAFTA was designed to stimulate economic growth by reducing trade restrictions and allowing goods to flow more freely among the three countries. Despite initial opposition due to concerns about job losses in industries such as manufacturing, the agreement has since enabled the establishment of the world's largest trading bloc in terms of population. This has had far-reaching implications for trade patterns, industrial activity locations, and even migration dynamics within the member countries.