You administer a Microsoft SQL Server 2012 database that contains a table named OrderDetail.
You discover that the NCI_OrderDetail_CustomerID non-clustered index is fragmented. You need
to reduce fragmentation. You need to achieve this goal without taking the index offline. Which
Transact-SQL batch should you use?

A.
CREATE INDEX NCI_OrderDetail_CustomerI D
ON OrderDetail.CustomerID WITH DROP EXISTING

B.
ALTER INDEX NCI_OrderDetail_CustomerID
ON OrderDetail.CustomerID REORGANIZE

C.
ALTER INDEX ALL
ON OrderDetail REBUILD

D.
ALTER INDEX NCI_OrderDetail_CustomerID
ON OrderDetail.CustomerID REBUILD

Explanation:
http://msdn.microsoft.com/en-us/library/ms188388.aspx