Final answer:
B) epidemic typhus Malaria is not caused by a bacterium; it is caused by Plasmodium parasites. In contrast, relapsing fever, epidemic typhus, plague, and tickborne typhus are all bacterial infections.
Step-by-step explanation:
The condition that is NOT caused by a bacterium is malaria. Malaria is caused by a Plasmodium parasite, not a bacterium. It is transmitted through the bite of infected Anopheles mosquitoes. In contrast, relapsing fever can be caused by bacterium Borrelia spp, and antibiotic treatments are effective against it.
Epidemic typhus is caused by Rickettsia prowazekii, spread by body lice. The bacteria Yersinia pestis is responsible for plague, and tickborne typhus is attributed to bacteria such as Rickettsia species.
On the other hand, the other options listed in the question (relapsing fever, epidemic typhus, plague, and tickborne typhus) are all caused by bacteria. For example, relapsing fever can be caused by bacteria of the genus Borrelia, whereas epidemic typhus is caused by the bacteria Rickettsia prowazekii, and plague is caused by the bacteria Yersinia pestis.