How is evolution affected by the increase in oxygen caused by the first photosynthesis organisms

Which mantle is under the crust the upper mantle or the lower mantle i think it's upper let me know if i'm right

What are some things that limit population growth?

One statements is an example of a scientific observation. another statement is an example of a scientific explanation. identify the correct statement for each category to illustrate how scientific explanations are inferred from scientific observations.