Which TransactSQL statement should you use?

You are a database developer of a Microsoft SQL Server 2012 database. You are designing a table
that will store Customer data from different sources. The table will include a column that contains
the CustomerID from the source system and a column that contains the SourceID. A sample of this
data is as shown in the following table.

You need to ensure that the table has no duplicate CustomerID within a SourceID. You also need to
ensure that the data in the table is in the order of SourceID and then CustomerID. Which TransactSQL statement should you use?

A.
CREATE TABLE Customer
(SourceID int NOT NULL IDENTITY,
CustomerID int NOT NULL IDENTITY,
CustomerName varchar(255) NOT NULL);

B.
CREATE TABLE Customer
(SourceID int NOT NULL,
CustomerID int NOT NULL PRIMARY KEY CLUSTERED,
CustomerName varchar(255) NOT NULL);

C.
CREATE TABLE Customer
(SourceID int NOT NULL PRIMARY KEY CLUSTERED,
CustomerID int NOT NULL UNIQUE,
CustomerName varchar(255) NOT NULL);

D.
CREATE TABLE Customer
(SourceID int NOT NULL,
CustomerID int NOT NULL,
CustomerName varchar(255) NOT NULL,
CONSTRAINT PK_Customer PRIMARY KEY CLUSTERED
(SourceID, CustomerID));