Which of the following is a method for sending real-time notifications to users based on data changes?

Real-time notifications to users based on data changes are best accomplished through user interface updates. In the context of Salesforce and similar systems, this method allows for immediate feedback on data changes, ensuring that users are informed as events occur. For example, if a case is updated or a new lead is created, an interface update can reflect these changes instantly, allowing users to respond promptly, improving engagement and efficiency.

The other methods mentioned do not align with the need for real-time notifications. Web service callouts are typically used for integrating external systems rather than directly alerting users. Batch data imports involve processing large sets of data at scheduled times and do not provide immediate updates. Scheduled data exports similarly operate on a fixed timetable, meaning they cannot provide real-time information as the data changes. Therefore, the user interface update method effectively serves the need for timely communication regarding data changes to users.