A legal document authorizing someone else to represent you is called a:

The correct choice is the Power of Attorney (POA), which is a legal document that allows one person to act on behalf of another in legal or financial matters. This document designates the representative, known as the agent or attorney-in-fact, who can make decisions and take actions as specified within the document. The POA can cover various matters, including managing financial affairs, making healthcare decisions, and handling real estate transactions.

By designating someone through a POA, the principal (the person granting the authority) can ensure that their wishes are carried out, especially in circumstances where they may be unable to make decisions themselves due to illness or absence. The power given can be broad or limited, depending on the stipulations set forth in the document.

In contrast, a promissory note is a financial instrument that represents a written promise to pay a specified amount of money to a specified person. A trust deed is a legal document associated with real estate transactions that outlines the relationship between a borrower and a lender. A contractual agreement is a mutual arrangement between two or more parties that creates legally binding obligations but does not specifically denote the representation of one party by another in a legal sense.