A. factors of production are free to move and be moved
B. common currency is in use
C. common agricultural policy is in place
D. the size of the market is widened
Option A – factors of production are free to move and be moved
Economic integration forms international co-operation among nations to foster their economic interests. Countries with common interests form themselves into an organisation whose major objectives are to remove trade barriers and other obstacles that reduce the free flow of goods and service between them.