Why do you think DNA is duplicated before a cell divides? Why do you think the sister chromatids
are attached to one another?

The two cells that result from a single cell need to have the same amount of genetic material as the initial cell, therefore the DNA needs to be duplicated before the cell divides.

The sister chromatids are attached together so that during anaphase the daugther cells will receive the same chromosomes

sorry to break it to ya but no one can answer your question it's just

jk but i am serious about the part that most people cant answer it beacuse you did not mention the section you are talking about. but it would if you added some detail and were a bit more specific.