During 1976 a series of arsons, one of which damaged the Humongous Store, occurred in the City of Swelter. In early 1977 Swelter's City Council adopted this resolution: The City will pay $10,000 for the arrest and conviction of anyone guilty of any of the 1976 arsons committed here. The foregoing was telecast by the city's sole television station once daily for one week. Subsequently, Humongous, by a written memorandum to Gimlet, a private detective, proposed to pay Gimlet $200 "for each day's work you actually perform in investigating our fire." Thereafter, in August 1977, the Swelter City Council by resolution repealed its reward offer and caused this resolution to be broadcast once daily for a week over two local radio stations, the local television station having meanwhile ceased operations. In September 1977, a Humongous employee voluntarily confessed to Gimlet to having committed all of the 1976 arsons. Humongous's president thereupon paid Gimlet at the proposed daily rate for his investigation and suggested that Gimlet also claim the city's reward, of which Gimlet had been previously unaware. Gimlet immediately made the claim. In December 1977, as a result of Gimlet's investigation, the Humongous employee was convicted of burning the store. The city, which has no immunity to suit, has since refused to pay Gimlet anything, although he swears that he never heard of the city's repealer before claiming its reward"In which of the following ways could the city reward offer be effectively accepted?
Only by an offeree's return promise to make a reasonable effort to bring about the arrest and conviction of an arsonist within the scope of the offer. Only by an offeree's making the arrest and assisting in the successful conviction of an arsonist within the scope of the offer. By an offeree's supplying information leading to arrest and conviction of an arsonist within the scope of the offer. By an offeree's communication of assent through the same medium (television) used by the city in making its offer.