Which of the following repository objects offer a preview function?

The preview function provides a way to visualize or analyze the structure and elements of a particular repository object before final implementation or usage. In the context of the SAP environment, Data Definitions are pivotal as they define the structure of data types, including fields, data types, and associations.

When using the preview function for Data Definitions, a developer can check the content layout and understand how the data will be structured in a database table or data model. This capability is crucial for developers as it aids in validating the design, ensuring that it meets the required specifications before implementing it into the system.

Behavior Definitions, Service Bindings, and Service Definitions, while important components in the development environment, typically focus on other functionalities such as defining application logic or how services interact with other system components, rather than providing a structured preview of data model layout.