You are designing a strategy for synchronizing two geographically disparate SQL Azure databases.  A database named DB1 is located in North America. A database named DB2 is located in Asia.  DB2 contains a subset of the tables in DB1.  You need to recommend an approach for bidirectionally synchronizing the databases each day.  What should you recommend？（）

• A、 Use SQL Azure Data Sync.
• B、 Use custom Microsoft Sync Framework metadata.
• C、 Use a Microsoft Sync Framework Partial Participant.
• D、 Use a Microsoft Sync Framework file synchronization provider.