The correct answer is: C. Nucleoid
The nucleoid is a region of a prokaryotic cell that contains all of the genetic material. It is not surrounded by a nuclear membrane, as is the nucleus of a eukaryotic cell. The nucleoid is typically a dense, irregularly shaped mass of DNA and associated proteins.
The nucleolus is a small, dense organelle found in the nucleus of eukaryotic cells. It is involved in the synthesis of ribosomes, which are the protein-synthesizing organelles of the cell.
The centrosome is a small, non-membranous organelle found in animal cells. It is involved in cell division, and contains the centrioles, which are the microtubule-organizing centers of the cell.
The nucleus is a large, membrane-bound organelle found in eukaryotic cells. It contains the cell’s DNA, which is organized into chromosomes. The nucleus is also involved in the regulation of gene expression, and in the synthesis of proteins.