All of these restrict international trade except trade deficits.
Trade deficit is an economic measure of a negative balance of trade in which a country's imports exceeds its exports. A trade deficit represents an outflow of domestic currency to foreign markets
The correct answer between all the choices given is the last choice or letter D. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.