What conditions need to be maintained at a certain level in the human body for survival

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures

Why does the earth spin slowly, not faster? is it possible to prove it scientifically? can you prove it with math?

Which are evidence of seafloor spreading? check all that apply. molten material magnetic stripes continent material drilled core samples ocean water samples