Where did the first inhabitants of the Americas migrate from?

The settlement of the Americas is widely accepted to have begun when Paleolithic hunter-gatherers entered North America from the North Asian Mammoth steppe via the Beringia land bridge, which had formed between northeastern Siberia and western Alaska due to the lowering of sea level during the Last Glacial Maximum

Explanation:

answer; i believe that the correct answer is (c) arctic tundra;

the graph shows the spread of railways in the 1800s.

based on the graph, the conclusion that can be drawn about germany is answer d)   by 1880, germany had more rail lines than great britain and russia.