Your company has an Exchange Server 2010 organization. A user named User1 is configured as a Delegate for a user named User2. You need to ensure that User1 can add User2 in the From field when sending email messages. Messages that contain User2 in the From field must display User2 as the message sender when recipients receive the messages.  What should you do（）？ 

• A、Remove User1 as a delegate， and then grant User1 Send As permissions to User2¯s mailbox
• B、Remove User1 as a delegate， and then grant User1 Send on Behalf permissions to User2¯s mailbox
• C、Create a Sharing policy， and then grant User1 Modify permissions to User2¯s mailbox
• D、Create a Sharing policy， and then grant User1 Full Mailbox permissions to User2¯s mailbox