Which of the following is an example of a bio-safety level 4 agent?

Ebola is classified as a biosafety level 4 (BSL-4) agent due to its high risk of transmission and severe health consequences. BSL-4 agents are characterized by their ability to cause life-threatening disease in humans or animals, often with no known treatments or vaccines. They require the highest level of containment, including specialized laboratories designed to prevent any exposure, with strict procedures to minimize the risk of inhalation or skin contact.

Other organisms listed, such as E. coli and Salmonella, typically fall under lower biosafety levels. These organisms are important pathogens but do not present the same extreme risk as BSL-4 agents. Chlamydia, while it poses health issues, primarily affects reproductive health and does not meet the criteria for a biosafety level 4 categorization. Thus, Ebola, with its severe pathogenicity and transmission challenges, is the sole example here that aligns with the distinct characteristics of a BSL-4 agent.