International Trade Is a Federal Responsibility, but Provinces Have a Role

International trade is a federal responsibility, but provinces have a role to play in the regulation of international commercial matters because

A) of their power over property and civil rights which means that some rules regarding international trade must be implemented through provincial law, such as the United Nations Convention on Contracts for the International Sale of Goods.
B) they have traditionally had power over interprovincial and international trade.
C) of a federal- provincial agreement that they should.
D) they set standards for consumer protection that protect consumers both in Canada and abroad.
E) Canada's Constitution is silent as to the level of government with exclusive responsibility over international trade.