You work in a company which uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of two SQL Server 2008 instance. The two instances are respectively named InstanceA and InstanceB. There is a database named Dworks on InstanceA. You move the Dworks database to InstanceB. A user use a SQL Server login named Mary to access the database on InstanceA with the password "Tk@87#34". On InstanceB, you create the same SQL Server login. The user tries to use the SQL Server login Mark to access the Dworks database on InstanceB. But the user gets an error message, according to the indication of the message, the access to the Dworks database has been denied. You must make sure that the user can access the Dworks database on InstanceB successfully.  So on InstanceB, which Transact-SQL statements should you execute?（）  

• A、USE AdventureWorks;ALTER USER Mary WITH LOGIN = Mary; 
• B、USE AdventureWorks;ALTER LOGIN Mary ENABLE; 
• C、USE AdventureWorks;ALTER LOGIN Mary WITH PASSWORD = "Tk@87#34" UNLOCK; 
• D、USE AdventureWorks;ALTER LOGIN Mary WITH DEFAULT_DATABASE = AdventureWorks;