A mortgage lien is best described as:

A mortgage lien is a legal claim against a property that serves as collateral for a loan. When a borrower takes out a mortgage to purchase a home, the lender places a lien on that specific property, meaning that the lender has the right to take possession of the property if the borrower defaults on the loan. This security interest is crucial for lenders, as it mitigates the risk of lending money for the purchase of real estate.

The description of the mortgage lien as a secured loan emphasizes that the loan is not just based on the borrower’s creditworthiness but is also backed by the asset—the property itself. If the borrower fails to make the required payments, the lender can initiate foreclosure proceedings to reclaim the property. This makes the lender more secure in their investment compared to unsecured loans, where there are no specific assets tied to the debt.

In contrast, other options suggest unrelated concepts. The idea of requiring joint ownership doesn't pertain directly to the nature of a mortgage lien itself. An unsecured debt obligation refers to loans that do not have collateral, making this irrelevant to the context of a mortgage. Lastly, a lien against all properties owned indicates a broad claim that is not characteristic of a mortgage lien, which specifically attaches to a particular asset. Thus, option B