Why does the DNA that makes up the chromosomes need to replicate before the start of meiosis?

The image shows embryos of three vertebrate classes

This is a type pf behavior that animals are born with and them to survive

Sarah and john are having a discussion on genetic diversity. sarah believes that it happen over a long period of time. john it happens immediately. who is correct? a. sarah is correct because genetic diversity occurs over a long period of time. b. john is correct because genetic diversity occurs immediately. c. both are correct because genetic variation can occur or long period of time. d. neither are correct because genetic diversity occurs over any period of time