(1) Which is the best example of a physical region?

Question

a. Mexico, b. Sea/Japan c. European Economic Union or the french speaking province of Quebec?

Answer 1

The Sea of Japan - the area has an arbitrary name, but it has a distinct physical definition.

The others (Mexico, European Economic Union, French Canada) are all arbitrary man-made political, economic and linguistic (respectively) regions that depend on Man to have meaning. They have no physical reality without it being given by Man.

Can you point to the edges of the Sea of Japan from space? Yes.

Can you point to the edges that define Mexico, European Economic Union and French Canada from space? No - not without a political map.