Which document formally records the sale of real estate?

The warranty deed is the correct answer because it serves as the legal instrument that formally conveys ownership of real estate from the seller to the buyer. This document includes essential information such as the names of the parties involved, a description of the property, and any warranties regarding the title. The warranties provided in the deed assure the buyer that the seller has the right to sell the property and that there are no undisclosed encumbrances.

Other documents mentioned serve different purposes. A mortgage is primarily a security instrument that establishes a lender's interest in the property as collateral for a loan. A lease agreement outlines the terms under which a tenant occupies property owned by a landlord but does not transfer ownership. A title insurance policy protects against potential defects in the title but does not itself record the actual sale. Thus, the warranty deed is the primary document used to officially record the sale of real estate.