Final answer:
The DNA-containing region of a bacterial cell is called the nucleoid, denoted by answer 'C'. Bacterial cells are prokaryotic and have their genetic material located in this nucleoid region without a surrounding membrane.
Step-by-step explanation:
The DNA-containing region of a bacterial cell is referred to as the nucleoid. This location within the bacterial cell is where the single, circular chromosome and possibly additional plasmids are located. The correct answer to the student's question, denoting this region, would be “C”, according to the provided diagram and information.
Bacteria are prokaryotic organisms, meaning they lack a defined nucleus and instead, have a nucleoid where their DNA is located. This nucleoid region contains the cell's genetic information but is not surrounded by a membrane as it would be in eukaryotic cells. Plasmids present in bacteria are smaller loops of DNA that can be exchanged between bacteria, sometimes carrying important traits like antibiotic resistance.