Eukaryotic cells have many different molecules which control the cell as it goes through the cell cycle. which of these would not be a valid reason for a cell's need to have these control molecules present?

It seems that you have missed the given option for this question but anyway, here is the answer. The statement that would not be a valid reason for a cell's need to have these control molecules present is that they make it impossible for the cell cycle to occur out of order. Hope this is the answer that you are looking for.