What is nucleosome?

Negatively charged DNA wrapped around the positively charged histone octamer

The correct answer is Option (3) → Negatively charged DNA wrapped around the positively charged histone octamer 

In eukaryotes, there is a set of positively charged, basic proteins called histones. A protein acquires charge depending upon the abundance of amino acids residues with charged side chains. Histones are rich in the basic amino acid residues lysine and arginine. Both the amino acid residues carry positive charges in their side chains. Histones are organised to form a unit of eight molecules called histone octamer.

The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome . A typical nucleosome contains 200 bp of DNA helix. A nucleosome consists of nine histone proteins: a core histone octamer—comprising two copies each of H2A, H2B, H3, and H4—and a single linker histone, H1. The linker histone attaches to the DNA segment outside the core particle, playing a key role in chromatin compaction.

                    Nucleosome