The phase in the cell cycle where the double stranded chromosomes are pulled apart.

The phase of the cell cycle (also known as Mitosis) where double stranded/replicated chromosomes are being puller apart is called Anaphase. Sister chromosomes (the replicated chromosomes) are pulled to opposite poles of the cell and split from the double stranded/replicated chromosome. They are no longer chromatids and now separate chromosomes.

Anaphase

Explanation:

The prefix "Ana" means apart.

The phases are:

Prophase - DNA becomes chromosomes and nucleus disappears

Metaphase - chromosomes align in the middle; "meta" is middle

Anaphase - chromosomes pulled apart

Telophase - chromosomes becomes DNA in their new cells, nucleus reappears