Oscar, the owner in fee simple, laid out a subdivision of 325 lots on 150 acres of land. He obtained governmental approval (as required by applicable ordinances) and, between 1968 and 1970, he sold 140 of the lots, inserting in each of the 140 deeds the following provision: "The Grantee, for himself and his heirs, assigns and successors, covenants and agrees that the premises conveyed herein shall have erected thereon one single-family dwelling and that no other structure (other than a detached garage, normally incident to a single-family dwelling) shall be erected or maintained; and, further, that no use shall ever be made or permitted to be made other than occupancy by a single family for residential purposes only." Because of difficulty encountered in selling the remaining lots for single-family use, in January 1971, Oscar advertised the remaining lots with prominent emphasis: "These lots are not subject to any restriction and purchasers will find them adaptable to a wide range of uses.""Suppose that Oscar sold 50 lots during 1971 without inserting in the deeds any provisions relating to structures or uses. Doyle purchased one of the 50 lots and proposes to erect a service station and to conduct a retail business for the sale of gasoline, etc. Pringle purchased a lot from Boyer. Boyer had purchased from Oscar in 1968 and the deed had the provision that is quoted in the fact situation. Pringle brings suit to prevent Doyle from erecting the service station and from conducting a retail business. In the litigation between Pringle and Doyle, which of the following constitutes the best defense for Doyle?
Oscar's difficulty in selling with provisions relating to use establishes a change in circumstances which renders any restrictions which may once have existed unenforceable. Enforcement of the restriction, in view of the change of circumstances, would be an unreasonable restraint on alienation.  Since the proof (as stated) does not establish a danger of monetary loss to Pringle, Pringle has failed to establish one of the necessary elements in a cause of action to prevent Doyle from using his lot for business purposes.  The facts do not establish a common building or development scheme for the entire subdivision.