Anne loaned David money to start a business, which later failed. David offered to sign a promissory note for the debt to prevent Anne from instituting legal proceedings against the remaining assets of the failed business. Anne agreed, but would only accept a note cosigned or indorsed by Donna, David’s mother. Donna signed the back of her son’s note. Anne later sued Donna to collect the note when David could not be located. What type of party does Donna represent? Is Donna liable?