You create a Web site with membership and personalization enabled. You must use an existing CRM database for storing the membership information. You need to implement the Membership Provider. What should you do?（）

A.Modify the connection string in the Web.config file to connect to the CRM database.

B.Add new a SqlMembershipProvider to the Web.config file.

C.Create a custom Membership Provider inheriting from MembershipProvider.

D.Create a custom MembershipUser inheriting from MembershipUser.