When did oxygen levels start to decline from 35 percent down to today’s levels

How would i answer this for an exam?

How did the environment influence settlement patterns in colonial america? * 1 point a. early settlers stayed near rivers for farmland and transportation b. early settlers stayed in hilly areas to avoid frequent floods in coastal areas c.early settlers quickly moved to the mountains to avoid hot summers d. early settlers only lived on coastal islands to prevent indian attacks

Because of their geographic similiarities, the nordic nations also have similar a. cultures c. religions b. economic activities d. all of the above