单项选择题
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 application is utilized by the company. A query is executed by the application to return three columns of the nvarchar data type and one column of the XML data type. A WHERE clause is utilized by the query， and all three of the nvarchar columns are contained by the WHERE clause. 5 million rows are included by the table， and 50，000 rows are returned by the query. The performance of the query should be enhanced.
Which action should be performed to achieve the goal？（）
A.A primary XML index should be created on the XML column.
B.Statistics should be created on the nvarchar columns.
C.A view should be created， and only the four columns that the query utilizes are contained by a view.
D.A composite index should be created on the three nvarchar columns， and INCLUDE should be specified for the XML column.