Which microorganisms are included in biological agents?

The correct answer encompasses a range of pathogenic microorganisms that can cause significant harm to human health and the environment. Biological agents include bacteria, fungi, Rickettsiae, and viruses, all of which are capable of causing diseases or producing toxins that can lead to serious health issues, particularly in the context of biological warfare or bioterrorism.

Bacteria are unicellular microorganisms that can reproduce independently and include pathogens like anthrax and plague. Fungi can also be dangerous; some species produce mycotoxins that can cause various health problems. Rickettsiae are a group of bacteria that are typically transmitted to humans through arthropod vectors, leading to diseases such as typhus. Viruses, from the common cold to more severe pathogens like Ebola, are infectious agents that replicate only within living host cells.

In contrast, options that include microorganisms like amoebas and worms do not fit the definition of biological agents as effectively. While some amoebas can be pathogenic, they are not as widely recognized as a category of biological agents in the same way that bacteria, fungi, Rickettsiae, and viruses are. Furthermore, worms typically refer to multicellular parasites and are less relevant in the context of biological agents commonly discussed in military or