Reasons to use native XML features in SQL Server instead of managing your XML data in the file system would be:
All options are correct
Well Done. Your Answer is Correct Keep it Up!
You need language support for query and data modification for cross-domain applications
You want the server to guarantee that the data is well formed and also optionally validate your data according to XML schema
You want indexing of XML data for efficient query processing and good scalability, and the use of a first-rate query optimizer