You work in a company which is named Wiikigo Corp. The company 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. The company stores clients data in DB1. Clients can access their profile data by using a Web application. You must ensure the security of the customer data, you must ensure that even if the backup media is lost, data files, log files and subsequent backups and so on are quite safe. 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 level. 
• 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.