The correct option is D Nucleosomes Chromatin refers to the complex of nucleic acids and associated proteins that make the eukaryotic chromosomes. Options A and B are incorrect.
Option C is incorrect as nuclear matrix is the network of fibres present inside the nucleus and is not the part of chromatin. Nucleosomes are fundamental organizational units of chromatin which appear as “beads-on-a-string” arrangement. Each bead of nucleosome has 200 bp of DNA which is wound 1.65 times around histone octamer. The bead plus linker DNA leads to the next bead and form the nucleosomes. Nucleosomes are coiled to form a 30-nanometer chromatin fiber, which forms 300 nm long loops. These 300 nm fibres are again folded to produce a 250 nm fibre that is tightly coiled into the chromatid of a chromosome.