Here's a breakdown:

* Chromosomes are structures made up of tightly coiled DNA and proteins. They are found in the nucleus of eukaryotic cells (cells with a membrane-bound nucleus).

* DNA (deoxyribonucleic acid) is the genetic material that carries the instructions for building and maintaining an organism.

* The nucleus is the control center of the cell, containing the chromosomes and therefore the genetic material.

So, it's the DNA that is packed inside the nucleus, organized into chromosomes.