Read the following statements and select the correct statements in relation to the conclusions of Darwin:

I) The fitness, according to Darwin, refers ultimately and only to reproductive fitness.

II) Embryos never pass through the adult stages of other animals. 

III) The existing living forms share similarities to varying degrees not only among themselves but also with life forms that existed millions of years ago.

IV) The diversity of living organisms was always the same since creation and will be the same in future also.