"sell a country! why not sell the air, the great sea, as well as the earth? did not the great spirit make them all for the use of his children? " – tecumseh, shawnee leader can someone explain what this means to you?

This idea means that a nation cannot be sold. Tecumseh believes that "a country" is for everyone to use; it is not a commodity.

He compares a country to the air and the sea -- these things cannot be sold; they are too great to sell. They are for everyone. He says a country is the same -- it is universal, not sellable. 

I’m going to guess #4 since that seems pretty logical.