Here's why:

* Eukaryotic cells are complex cells that have a membrane-bound nucleus where their genetic material (DNA) is stored.

* Chromosomes are essentially long, tightly coiled strands of DNA that carry genetic information.

* The nucleus acts as a control center for the cell and protects the chromosomes from damage.

While the chromosomes reside in the nucleus, they are not visible most of the time. They become visible and condense during cell division (mitosis or meiosis).

Let me know if you have any other questions!