Final answer:
The document that secures a property as collateral in the event of nonpayment of a debt is called a mortgage. This legal agreement binds the borrower to repay the loan and permits the lender to foreclose on the property if payments are not made.
Step-by-step explanation:
The document that specifies that a property is being used as security in the event of nonpayment of a debt is the mortgage. When a borrower takes out a loan to purchase property, the lender often requires the property as collateral for the loan. The mortgage legally binds the borrower to repay the debt and provides the lender the right to take possession of the property if the borrower fails to make payments.
A title deed is a document that proves ownership of a property, while a promissory note is a written agreement to repay a certain amount of money over a specified period. A warranty deed, on the other hand, guarantees that the property owner holds a clear title to a piece of real estate and has the right to sell it. However, it is the mortgage that specifically secures the property as collateral.