The nucleosome is Bubepure agun oreen a. DNA and 8 histone molecules b. metaphase chromosome c. double stranded DNA structure d. chromotin fibril with a diameter of 30 nm

The correct answer is a. DNA and 8 histone molecules.A nucleosome is the basic unit of DNA packaging in eukaryotic cells. It consists of a segment of DNA wrapped around a core of eight histone proteins. The DNA is wrapped around the histone core in a supercoiled structure, which helps to compact and organize the DNA within the cell nucleus.The other options are not correct:b. Metaphase chromosome: This refers to the condensed and highly coiled structure of DNA that is visible during cell division, specifically during the metaphase stage. It is not the same as a nucleosome.c. Double stranded DNA structure: While DNA is indeed double-stranded, this option does not accurately describe the specific structure of a nucleosome.d. Chromatin fibril with a diameter of 30 nm: Chromatin is the complex of DNA and proteins (histones) that makes up the contents of the nucleus of a eukaryotic cell. The 30 nm chromatin fibril is a higher-order structure that is formed by the coiling and folding of nucleosomes, but it is not the same as a single nucleosome.Therefore, the correct answer is a. DNA and 8 histone molecules.