You work in a company which uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of a SQL Server 2008 instance. There is a database named DB1 in the instance. VIP customer data of the company are stored in DB1. The customers access their profile data by using a Web application. You must ensure the security of the customer data， that is to say， even if the backup media is lost， you must guarantee that data files， log files and subsequent backups and so on are as safe as possible.  So what action should you perform to achieve this goal？（）

• A、For both the CustomerDB database and the master database, enable Transparent Database Encryption 
• B、You should use the built-in encryption functions to encrypt the sensitive data at the cell Ievel 
• C、You should make the CustomerDB database accessible only through stored procedures and functions. 
• D、For the CustomerDB database, enable Transparent Database Encryption and back up the transaction log.