Why Do Larger Countries Tend to Have Lower Ratios of International

Why do larger countries tend to have lower ratios of international trade to GDP than smaller countries?

A) Larger countries tend to have more trade between states or provinces within their borders than smaller countries.
B) Larger countries tend to have higher tariffs than smaller countries.
C) Larger countries tend to trade with other larger countries.
D) Larger countries tend to have larger trade deficits than smaller countries.