Answer this simple question ! (reporting if incorrect)

Which statement best explains distribution of natural resources? people tend to settle in locations that have the resources they need for survival. some countries have resources that others lack, so trade between countries becomes vital. fossil fuels come from areas that have mountains and other areas that manufacture synthetic gas. areas with natural resources provide a higher standard of living and better quality of life.

One of the main reasons societies settled along rivers in the neolithic era was because a) the village elders demanded it. b) the land there was more valuable. c) it was more safe and secure there. d) it provided irrigation for farming.

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4