Which type of organism is characterized by having a cell wall and lacking a nucleus?

The correct answer is characterized by the presence of a cell wall and the absence of a nucleus. Bacteria fall into the category of prokaryotic organisms, which means they do not have a membrane-bound nucleus. Their genetic material is found in a region of the cell called the nucleoid, which is not enclosed by a membrane.

Moreover, bacteria have a rigid cell wall made up of peptidoglycan, which provides structural support and protection. This distinguishes them significantly from eukaryotic organisms, which include plants, fungi, and animals. While plants and fungi also have cell walls, they both possess a nucleus and are eukaryotic. Animals, on the other hand, lack cell walls altogether and have complex cellular structures. Thus, the distinctive characteristics of bacteria—having a cell wall and being prokaryotic—confirm that this is the correct answer.