Answer: The correct option will be option d. The he European Union. It is the oldest and the largest free trade area in the World.
Explanation: Free Trade area is a kind of trade bloc created by various countries by signing a Free Trade Agreement. The Members of this bloc generally agree on reducing trade barriers and tariffs, amongst themselves. It aims at increasing trade between the countries and also promote free movements of people accross these territories.
So, European Union is the oldest and largest free trade area that came into being in the 1951 with 6 member nations namely- Italy, Belgium, Germany, Luxembourg, France and Netherlands. Currently it has 28 members, with Croatian being added tothe members list.