Reasons to use native XML features in SQL Server instead of managing your XML data in the file system would be:

• A. You need language support for query and data modification for cross-domain applications
• B. You want the server to guarantee that the data is well formed and also optionally validate your data according to XML schema
• C. You want indexing of XML data for efficient query processing and good scalability, and the use of a first-rate query optimizer
• D. All of the mentioned