Final answer:
In REA data models, an event is a transaction that results in changes in resources or agents. Thus, Sales is an event because it is a transaction involving a change in inventory and interaction with customers.
Step-by-step explanation:
In REA (Resources, Events, Agents) data models, an event is something that occurs at a specific time and place, can be described, and results in changes in resources or agents. In the context of the question, which of the following could be an event in REA data models, the answer is 2) Sales. Sales is considered an event because it is a transaction that involves a change in resources (typically inventory) and can affect agents (e.g., customers or salesperson). Cash is a resource, and Customer and Inventory are agents and resources respectively but they are not events themselves.