(A) NAFTA (North American Free Trade Association)- 

• U.S.A., Canada and Mexico (3)
• NAFTA was a trade agreement between the United States, Canada, and Mexico. It aimed to eliminate barriers to trade and investment among the member countries.

(C) SAFTA (South Asian Free-Trade Agreement)- 

• Bangladesh, Maldives, Bhutan, Nepal, India, Pakistan and Sri Lanka (7)
• SAFTA is an agreement among the South Asian Association for Regional Cooperation (SAARC) member countries to reduce and eliminate tariffs on goods traded among them.

(D) OPEC (Organisation of Petroleum Exporting Countries)- 

• Algeria, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, U.A.E. and Venezuela (11)
• OPEC is a group of oil-producing countries that collaborate to manage the production and pricing of oil to ensure stability in the oil market.

(B) EU (European Union)-

•  Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Netherlands and United Kingdom (28)
• The European Union is a political and economic union of member states, primarily located in Europe. It has a single market and a customs union, allowing for the free movement of goods, services, capital, and people among its member countries.