At which of the following levels can integration occur?

Integration can occur at several distinct levels within a system, and the correct answer identifies the comprehensive areas where this integration can be effectively executed.

The user interface level is where users interact with applications, enabling integration to support seamless data exchange and interaction between disparate interfaces. The application logic level refers to the functional programming of applications, where complex business processes and rules are defined, allowing for integrations that facilitate communication and processing between applications. Finally, the data level is crucial as it pertains to the management and sharing of data across different systems, ensuring that the data flows properly and is accessible for necessary operations.

Other options include elements that may not encapsulate the broadest aspects of integration. For instance, workflow rules, while part of business processes, do not represent the full scope of integration in the same way as application logic does. Similarly, aspects like reporting, although important, do not directly reflect the integration points where different systems can effectively combine and share information. Therefore, the selection that includes all three relevant areas—user interface, application logic, and data—truly captures the comprehensive nature of where integration can take place.