You are a professional level SQL Server 2005 database administrator in an international corporation named Wiikigo. You are experienced in implementing high-availability solutions， monitoring the database server， and design deployment. In the company， you major job is the deployment， maintenance and support of Microsoft SQL Server 2005. You work as a database administrator for your company. A SQL Server 2005 computer is managed by you， and a database named Customers is included by the SQL Server 2005 computer. A table named CustInfo is included by the database. An identity column named CustID and an nvarchar column named CustName are included by the table. According to the company requirement， rows which duplicate CustName values are included should be moved from the CustInfo table every year. However， the company requests to have rows removed from the CustInfo table after the rows have been manually examined and verified as being duplicates. Since you are the technical support， you are required to think out a method to have potential duplicate rows identified for manual examination. The minimum amount of administrative effort should be utilized. Which action should be performed to finish the task？（）

A trigger should be created for the CustInfo table so as to roll back INSERT queries that duplicate data is included.
B. A new unique index should be created on the CustName column. And then， IGNORE_DUP_KEY = ON should be specified when creating index.
C. On the CustName column， a foreign key constraint should be created， and a distinct list of CustName values is referenced by the foreign key constraint.
D. A SELECT INTO query should be utilized， and GROUP BY and HAVING clauses should be included by the query to create a new table that contains duplicate rows from the CustInfo table.