One advancement that has lowered the barriers many small firms face when building international sales isa. government-imposed quotas. b. air and railway systems. c. containerizationd. the Internet. e. JIT inventory systems.

The correct answer is letter "D": the Internet.

Explanation:

Over the past decades, the internet has been the factor influencing almost every aspect of the human lifestyle. It is not only a great resource of information and knowledge but it has also shaped the way entrepreneurs do business. With a couple of clicks, buyers and sellers from different parts of the world can settle transactions without the need for a meeting.