What type of policy protects against loss due to defects or unmarketability of the owner's title?

The correct choice is the Owner's Policies. This type of title insurance specifically protects the property owner from financial losses due to defects in the title or issues that may render the title unmarketable. An Owner’s Policy generally covers a wide range of problems, including errors in public records, unknown liens, or claims by others which may assert an interest in the property.

This policy provides assurance to the owner that their investment in the property is secure and that they will not face unexpected legal complications related to the title's validity. Having an Owner's Policy can be critical for homeowners, as it safeguards their ownership rights and offers peace of mind.

The Lender's Policies, on the other hand, are designed to protect the interests of the lender in the event that a title defect affects the mortgage. Mortgage Insurance relates primarily to protecting lenders against borrower defaults rather than issues with the title itself. Lastly, Title Guarantee is not a standard term used to refer to a specific type of title insurance policy in this context, making it less relevant as an option here.