You are a database administrator for a toy manufacturing company named NetFx. The company stores all itsproduct-related data in a database named Netfx_data that resides on a SQL Server 2008 server named Server1 . A table named Invoice_details exists in the database and contains the details of all the new invoices generatedby the company in the last month.
The table was created by using the following CREATE TABLE statement:
CREATE TABLE Invoice_details (
Invoice_id int NOT NULL,
Customer_id int NOT NULL,
Invoice_date datetime DEFAULT GETDATE () NULL,
Amount_total int NULL,
Serial_num int IDENTITY (1,1) NOT NULL)

A clustered index exists on the Serial_num column, and a composite nonclustered index exists on the Invoice_id and the Customer_id columns.
An application will be used to execute queries to retrieve all the invoices for a particular customer. The followingquery is used by the application to retrieve data:
SELECT Customer_id, Invoice_id, Invoice_date
FROM Invoice_details
WHERE Customer_id = 1234
ORDER BY Invoice_date DESC;

You must ensure optimal performance of the query. Which action should you perform to achieve this?