Concept:Free trade refers to trade between countries with no tariffs or quotas restricting the movement of goods and services.
Explanation:In economic integration, a free trade area is formed when member countries remove trade barriers among themselves.
Each member is still allowed to set its own external barriers against non-members.
This matches option A exactly.
Option B, where factors of production are mobile, describes a common market.
Option C, where members adopt a common external tariff, describes a customs union.
Option D, where members adopt common fiscal and economic policies, describes an economic union.
Therefore, the correct option is A.
Answer:A. each member operates its own barriers against non-members