Final answer:
MERCOSUR, or the Common Market of the South, was established by Argentina, Brazil, Paraguay, and Uruguay through a treaty. It aims to promote economic development and trade among member countries.
Step-by-step explanation:
MERCOSUR, also known as the Common Market of the South, is a trade bloc that was established by four countries: Argentina, Brazil, Paraguay, and Uruguay. These countries signed a treaty in 1991 to accelerate economic development and promote trade among them. Over the years, other countries like Venezuela and Bolivia have joined as full or associate members. However, Venezuela's membership was suspended in 2017 for failing to comply with democratic principles.
Keywords: MERCOSUR, Common Market of the South, trade bloc, Argentina, Brazil, Paraguay, Uruguay, treaty, economic development, Venezuela