Which type of pathogen is characterized by having a cellular structure?

Bacteria are living microorganisms that have a cellular structure, making them distinct from other types of pathogens. They comprise a single cell with a complex structure, including a cell membrane, cytoplasm, and genetic material, typically in the form of a singular circular chromosome. This cellular organization allows bacteria to carry out essential life processes such as metabolism, growth, and reproduction.

In contrast, viruses are acellular and lack the machinery necessary for independent metabolism and reproduction. They can only replicate within a host cell by hijacking the host's cellular processes. Prions, which are misfolded proteins, also lack a cellular structure and primarily propagate by inducing improper folding in normal proteins. Non-cellular pathogens encompass viruses and prions, further emphasizing their lack of cellular organization. Therefore, the characteristic of having a cellular structure specifically applies to bacteria among the given options.