What is an example of a viral biological agent?

The Ebola virus is indeed an example of a viral biological agent. It belongs to the family Filoviridae and is known for causing Ebola virus disease in humans and nonhuman primates. This virus is transmitted through direct contact with the bodily fluids of infected individuals and can lead to severe and often fatal disease due to its high virulence and rapid onset of symptoms, which include severe hemorrhagic fever.

In contrast, the other options presented are not viral agents. Bacillus anthracis is a bacterium that causes anthrax, Botulinum toxin is a potent neurotoxin produced by the bacterium Clostridium botulinum, and Plasmodium falciparum is a protozoan parasite responsible for the most severe form of malaria. Each of these agents has different methods of transmission, pathogenic mechanisms, and clinical manifestations, emphasizing the unique characteristics of viral agents like the Ebola virus.