You are designing an upgrade strategy for a Windows Azure application that includes one web role with one instance. You have the following requirements： - Test the application on the Windows Azure platform. - Ensure that application upgrades can be rolled back. - Ensure that upgrade and rollback processes do not cause downtime. You need to recommend an approach for upgrading the application. What should you recommend？（）
- A Deploy to the Production slot. Test the application， and then perform a VIP swap.
- B Deploy to the Staging slot. Test the application， and then perform a VIP swap.
- C Deploy to the Staging slot. Test the application， and then perform a manual in-place upgrade to the Production slot.
- D Deploy to the Staging slotTest the application， and then perform an automatic in-place upgrade to the Production slot.