Which Transact-SQL statement should you use?

You have a table named dbo.Customers. The table was created by using the following Transact-SQL statement:

CREATE TABLE dbo.Customers
(
CustomerID int IDENTITY(1,1) PRIMARY KEY CLUSTERED,
AccountNumber nvarchar(25) NOT NULL,
FirstName nvarchar(50) NOT NULL,
LastName nvarchar(50) NOT NULL,
AddressLine1 nvarchar(255) NOT NULL,
AddressLine2 nvarchar(255) NOT NULL,
City nvarchar(50) NOT NULL,
StateProvince nvarchar(50) NOT NULL,
Country nvarchar(50) NOT NULL,
PostalCode nvarchar(50) NOT NULL,
CreateDate datetime NOT NULL DEFAULT(GETDATE()),
ModifiedDate datetime NOT NULL DEFAULT(GETDATE())
)

You create a stored procedure that includes the AccountNumber, Country, and StateProvince columns from the dbo.Customers table. The stored procedure accepts a parameter to filter the output on the AccountNumber column. You need to optimize the performance of the stored procedure. You must not change the existing structure of the table. Which Transact-SQL statement should you use?

A.
CREATE STATISTICS ST_Customer_AccountNumber ON dbo.Customer (AccountNumber) WITH FULLSCAN;

B.
CREATE CLUSTERED INDEX IX_Customer_AccountNumber ON dbo.Customer (AccountNumber);

C.
CREATE NONCLUSTERED INDEX IX_Customer_AccountNumber ON dbo.Customer (AccountNumber) WHERE AccountNumber = ”;

D.
CREATE NONCLUSTERED INDEX IX_Customer_AccountNumber ON dbo.Customer (AccountNumber) INCLUDE (Country, StateProvince);