Negatively charged DNA is wrapped around histone octamer to form:

The correct answer is Nucleosome 

Explanation:

• The nucleosome, a section of DNA wrapped around a core of proteins, is the fundamental subunit of chromatin.
• Each nucleosome is comprised of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer. 
• The negatively charged DNA is wrapped around the positively charged histone octamer (protein) to form a structure called a nucleosome.
• Each nucleosome is comprised of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as histone octamer. 
• Each histone octamer is composed of two copies of each of the histone proteins H2A, H2B, H3, and H4. 
• A typical nucleosome contains 200 bp of DNA helix.
• Nucleosomes constitute the repeating unit of a structure in the nucleus called chromatin, threadlike stained (coloured) bodies seen in the nucleus.
• The nucleosomes in chromatin are seen as ‘beads-on-string’ structures when viewed under an electron microscope (EM).