In which order will free nucleotides add

Which of the following is an example of this type of co-evolution

Melting glaciers is a serious threat to the environment what is the possible consequence of melting glaciers on polar bears?

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