Final answer:
The major development in South America is the growth of intercountry trade and the progress toward free-market policies.
Step-by-step explanation:
The major development in South America is the growth of intercountry trade, spurred on by the progress toward free-market policies. This development has helped integrate South America with the global economy. The establishment of trade agreements and economic unions among the South American countries has become a standard method of securing business partnerships and enhancing economic opportunities within the region.