You have an Exchange 2010 organization.The organization contains a distribution group named Group1.You need to ensure that a user named User1 can add and remove members from Group1.You must prevent User1 from modifying all other groups. What should you do first？（）

• A、Add User1 to Group1 Managed by list.
• B、Assign User1 as a group moderator for Group1.
• C、Assign the Distributions Groups management role to User1.
• D、Assign the MyDistributionGroups management role to User1.