Which Transact-SQL statement should you use?

You are a database developer of a Microsoft SQL Server 2012 database.

The database contains a table named Customers that has the following definition:

You need to ensure that the CustomerId column in the Orders table contains only values that exist in the CustomerId column of the Customer table.

Which Transact-SQL statement should you use?
A . ALTER TABLE Orders
ADD CONSTRAINT FX_Orders_CustomerID FOREIGN KEY (CustomerId) REFERENCES
Customer (CustomerId)
B . ALTER TABLE Customer
ADD CONSTRAINT FK_Customer_CustomerID FOREIGN KEY {CustomerID) REFERENCES
Orders (CustomerId)
C . ALTER TABLE Orders
ADD CONSTRAINT CK_Orders_CustomerID
CHECK (CustomerId IN (SELECT CustomerId FROM Customer))
D . ALTER TABLE Customer
ADD OrderId INT NOT NULL;
ALTER TABLE Customer
ADD CONSTRAINT FK_Customer_OrderID FOREIGN KEY (OrderID) REFERENCES Orders
(OrderID);
E . ALTER TABLE Orders
ADD CONSTRAINT PK Orders CustomerId PRIMARY KEY (CustomerID)