Which factor most improved the exchange of information among countries? faster transportation reduced tariffs faster communication increased markets

The factor that is improved the exchange of  information among countries is : Faster Communication

In the past, when the change of information between countries is being done by letter, transportation would probably the one that improved it the most.

But currently, we exchange information between countries through electronic form of letter, which mean that we need fastr communication if we want to improve it

3. i would say one, but one is not prime nor composite.