A property owner has a mortgage on a lot and wants to borrow money to build a house on it. To accomplish this, which of the following clauses must the existing mortgage contain?

An alienation clause, also known as a due-on-sale clause, allows a lender to demand full repayment of the loan if the property is sold or transferred. This clause does not facilitate additional borrowing but rather restricts the transfer of ownership, making it irrelevant in the context of building a new house.

An acceleration clause enables the lender to require the full repayment of the loan upon default or other specified conditions. While it protects the lender's interests, it does not allow for the addition of a new loan for construction purposes, thus failing to meet the property owner's needs.

Subrogation refers to the legal right for an insurer or lender to pursue third parties to recover costs incurred. This clause is primarily related to insurance claims or debt repayment and does not directly relate to the restructuring of mortgage priorities necessary for obtaining new construction financing.