Choose one major transition in the form of life on earth (e.g., metabolism, cellular structure, multicellularity, habita

[answerhappygod]

Choose one major transition in the form of life on earth (e.g.,
metabolism, cellular structure, multicellularity, habitat). Discuss
at least three lines of evidence to support that this was in fact a
major line of transition. For each, describe the type of evidence,
how it is observed or measured, what assumptions are made and how
is it interpreted. Are there caveats or alternative
explanations that must be considered? What are they?