You are designing a web service that will be hosted in Windows Azure. The web service will accept and store structured and semi-structured data. The web service must meet the following requirements： - Update all data within a single transaction. - Enforce the data structure for structured data within the data store. You need to recommend an approach for storing the data. What should you recommend？（）

A. Use Windows Azure Queues.
B. Use a single SQL Azure database.
C. Use a single Windows Azure Drive.
D. Use Windows Azure Table storage.