What type of diagram would be used to show how the business reacts to an event?

A Business Process Model is the appropriate choice for illustrating how a business reacts to an event because it provides a detailed representation of the steps, activities, and workflows involved in a specific process. This type of model focuses on the sequence of actions that occur in response to various events and emphasizes the interaction between those actions and the resources involved. It allows for clear visualization of inputs, outputs, and decisions, making it easier to understand how an organization responds to specific triggers or changes within its operational environment.

In contrast, a Value Chain diagram typically illustrates the series of activities that add value to a product or service, rather than focusing specifically on reactive processes. An Organisational Model focuses on the structure and hierarchy of the organization itself, which does not directly address event-driven reactions. Similarly, a Business Activity Model outlines the functions and activities of a business but lacks the detailed sequence and flow needed to showcase reactions to particular events.