You administer a SQL Server 2008 instance. The instance hosts a database that is used by a Web-based application. The application processes 15,000 transactions every minute. A table in the database contains a column that is used only by the application. This column stores sensitive data. You need to store the sensitive data in the most secure manner possible. You also need to ensure that you minimize the usage of memory space and processor time. Which encryption type should you use?（）

• A、Symmetric key encryption
• B、Asymmetric key encryption
• C、Certificate-based encryption
• D、Transparent data encryption