You have the following requirements：   - Ensure that the business tier can be updated without affecting the application tier.   - Use the minimum role instance size that meets or exceeds the current server specifications.    You need to recommend a topology for hosting the application in Windows Azure.  What should you recommend？（）

• A、 Deploy the application tier and the business tier to one role with two Medium instances.
• B、 Deploy the application tier and the business tier to one role with two Large instances.
• C、 Deploy the application tier role to a Medium instance.  Deploy the business tier role to a medium instance.
• D、 Deploy the application tier role to a Large instance.  Deploy the business tier role to a Large instance.