Scenario or event trees are used to depict:

• A. Graphical depictions of bio pathways for hazard intro into a country
• B. They show only probabilities
• C. They replace all other analyses
• D. They show only outcomes with no branching

Answer: (B)

Scenario or event trees illustrate the sequence of events that can follow an initiating incident. They are drawn as branching diagrams where each node splits into possible next events, and each branch has a probability. Following a path from the start to an end state gives a specific scenario and its probability; the overall risk is obtained by multiplying the probabilities along the path. This visualization shows both the possible pathways and the outcomes they lead to, making it possible to see how likely each outcome is and which branches drive the risk. They’re not merely a display of probabilities, they don’t represent bio pathways in isolation, they don’t replace all other analyses, and they do involve branching rather than showing only a single end result.