Nucleus is the site of chromatin and chromosomes both.
Cell during resting phase/interphase or S1/S2, G1/G2 only has chromatin.
During M phase or at onset of cell division, chromatin unwinds and chromosome become apparent.
Chromatin is made of DNA wound to histone proteins and unit is called nucleosomes..
DNA represent gene coding sequences and promoters, entire genes in other words.
After cell division is complete, chromosomes again condense in form of chromatin.
Hope you can pickup the correct answer from above facts in combination with your text-book and glossary therein.