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Nucleosomes are the fundamental units of chromatin in eukaryotic cells and are primarily composed of DNA wrapped around histone proteins. Each nucleosome consists of a segment of DNA that is coiled around a core of histone proteins, which helps to compact the DNA and organize it within the nucleus. The packaging of DNA as nucleosomes serves several important functions, including the regulation of gene expression, DNA replication, and repair processes, as well as maintaining the overall structure and integrity of the chromosome during cell division.

The histones play a critical role in defining the structure and accessibility of DNA, impacting how genes are expressed and how the genetic material is manipulated during cellular processes. This organization is essential for DNA to fit into the nucleus of the cell and for executing the various cellular functions associated with the genome.

The other options presented fall short in accurately describing the composition of nucleosomes; they suggest incorrect components that do not form this key structure in chromatin.