Answer: Dunbar is, in fact, a surety and must satisfy the mortgage if Masters does not.
Step-by-step explanation:
A surety refers to the individual who makes a promise to be responsible for the debt obligation of a borrower on a situation whereby the borrower defaults and doesn't take responsibility. The surety is also known as the guarantor.
Since Masters defaulted in payment of the mortgage debt, but contends that Dunbar, is the original mortgagor, because he is primarily liable for the mortgage debt, then Dunbar is a surety and must satisfy the mortgage if Masters does not.