The correct answer is b. prokaryotes.
Eukaryotic v.s. Prokaryotic
You can recall that there are two major different types of cells: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus, and prokaryotic cells do not have a nucleus.
Bacteria, such as the streptococcus bacteria (which causes infections like strep throat and rheumatic fever), do not have a nucleus. This sets them apart from other types of cells. For instance, white blood cells (WBCs) do have a nucleus, but red blood cells do not.
Since bacteria are prokaryotic (do not have a nucleus), we cannot categorize them as eukaryotic. This renders option A incorrect.
Bacteria v.s. Viruses
Bacteria and viruses are also contrasting. Bacteria cause infections like pneumonia and skin infections (such as cellulitis), but viruses are in charge of most upper respiratory infections (URIs), like the common cold or the Novel Coronavirus.
As such, bacteria cannot be categorized under the viruses category. This means that option C cannot be correct.
Are archaea pathogenic?
Pathogens are different biological microorganisms that can cause infections. Both viruses and bacteria fall under this category. However, archaea are not known to create any type of disease in humans and are therefore marked as non-pathogenic.
As such, bacteria and archaea cannot make up a group of pathogenic organisms, so this means that option D is also incorrect.
The final answer choice that is correct is b. prokaryotes.