Final answer:
The lowest estate in real estate is a tenancy at sufferance, where a tenant occupies property without the landlord's permission following lease expiration.
Step-by-step explanation:
The lowest estate in real estate is: c. A tenancy at sufferance. This occurs when a tenant continues to occupy a property after their lease has expired, and the landlord has not granted permission for the tenant to remain. In contrast, a fee simple is the highest estate and represents absolute ownership. An estate at will gives the tenant the right to occupy the property with the consent of the owner which can be terminated at any time by either party. A condition fee usually refers to a fee simple that could end upon the occurrence of a specified condition, although it is not typically considered the lowest form of estate in real estate.