Table extensions in Dynamics 365 Finance and Operations allow developers to modify certain properties of a base table without over-layering. However, fundamental properties that define the table's core structure and behavior are locked. The CreatedBy property, which controls whether the system createdBy field is enabled on the table, is one of the properties that can be modified in a table extension. This allows developers to add user tracking to tables that did not originally have it. In contrast, properties like TableGroup, ConfigurationKey, and ClusteredIndex are considered foundational and cannot be changed via extensions to ensure the stability and integrity of the base application.

B. Table group: This is a fundamental property that defines the table's category (e.g., Main, Transaction). It cannot be modified in a table extension to preserve the intended data model.

C. Configuration key: This property is locked on the base table and cannot be changed in an extension. This restriction ensures consistent feature enablement and licensing behavior.

D. Clustered index: The clustered index is a core structural property of the base table that dictates the physical storage order of data. It cannot be altered by an extension.

1. Microsoft Learn. (2023). Table extensions - Finance & Operations | Dynamics 365. Microsoft Docs.

Reference: In the section "Properties on table extensions," the documentation explicitly lists the properties that can and cannot be changed. Created By is listed as a modifiable property, while Table Group, Cluster Index, and Configuration Key are listed as properties that cannot be changed in an extension.