Since World War II$,$ several factors have contributed to the rapid growth of international trade. These factors are:

transportation and communications technologies, and the general decline in the level of tariffs.

communication technology, general increase in the level of tariffs, and the transportation technology.

transportation technology, general increase in tariffs, and differences among nations in terms of production cost.

transportation technology, reductions in the number of participants, and the general increase in the level of tariffs.