Which of the following is an example of an encumbrance that makes a title unmarketable?

An encumbrance that makes a title unmarketable represents a claim or liability against the property that may hinder the owner's ability to sell it or deprive the buyer of full ownership rights. Mortgages are indeed a type of encumbrance that can make a title unmarketable because they represent a security interest in the property held by a lender. Potential buyers would view a mortgage as a debt obligation that needs to be satisfied before they can obtain full ownership. This is particularly significant because, if the mortgage is not paid, the lender has the right to foreclose on the property, which affects the buyer's rights and security.

In contrast, while public access easements and private restrictions might limit what a property owner can do with the land, they generally do not render the title unmarketable. An obsolete covenant, although it may not hold current relevance, does not inherently prevent a transfer of ownership. Therefore, while these other encumbrances impose certain limitations or conditions on property use, they do not constitute a barrier to marketability as significant as that created by outstanding mortgages.