All depended on natural resources for food and shelter" is the only option from the list that describes a way in which Native American groups were alike, but of course this varied.
Answer: increased surplus of natural resources
Explanation:
One country can sell the goods to another country. The countries need to trade because it used to help them to obtain things which they cannot produce, and which are necessary for their survival. This condition was also applicable on small scale groups or at the individual level. So, the natural and man-made resources used to get distributed among the members of the society and between the countries.
I would guess the Mediterranean Sea.