To check the ArcSDE geodatabase versioning information of a layer's feature class in an .mxd file, what should a user do?

Selecting the List by Sources button is the correct approach to check the ArcSDE geodatabase versioning information of a layer's feature class in an .mxd file. This option organizes layers based on their source data, allowing users to view properties of the data source, which includes the specific details pertaining to versioning for ArcSDE geodatabases.

When you choose this option, you can easily identify the geodatabase and its versioning status, making it straightforward to manage and understand the versioning of the feature class represented in the map document.

Other choices do not provide direct access to versioning information. The Show Full Paths button focuses on revealing the complete file paths of the data sources without extra details regarding versioning. The View Metadata button allows you to view descriptive information about a layer but does not necessarily reflect its versioning state. The View Map Document Properties button provides general information about the map document itself but does not contain specifics about feature class versioning within the geodatabase. Thus, for accessing comprehensive geodatabase versioning details, selecting the List by Sources button is the most effective option.