You need to declare a variable of the XML type named invoice

CORRECT TEXT
You have an XML schema collection named Sales.InvoiceSchema.
You need to declare a variable of the XML type named invoice. The solution must ensure that the
invoice is validated by using Sales.InvoiceSchema.
Provide the correct code in the answer area.

Answer: See the explanation

Explanation:
DECLARE @invoice XML(Sales.InvoiceSchema)