What challenges to automobiles bring to the U. S. & Canada?

These factors threaten north americas ecosystems

Impressions of tropical swamp plants were observed on rocks in polar regions. the impressions were dark black imprints, which means the fossils are examples of ( 1 ) the fossils tell us that polar regions ( 2 ) ( 1 ) a. carbonization b. mineralization c. trace fossils ( 2 ) a. had tropical plants that can grow in ice b. might have had a diffierent climate in the past c. will have abundent vegitation

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.