Walter Puts an Ad in the Paper as Follows: "$500

Multiple Choice

Walter puts an ad in the paper as follows: "$500 reward for the return of my golden ring." Albrecht finds the ring and returns it to Walter,but he refuses to pay Albrecht the $500.Which of the following statements is true regarding this case?

A) Because the ad was merely a solicitation of offers,there was no contract until Walter accepted Albrecht's offer to find the ring.
B) Albrecht may not recover the money because he did not contact Walter before he began his search.
C) Because Albrecht did not pay Walter to keep the offer open,Walter is free to revoke and need not pay Albrecht anything.
D) The ad was an offer for a unilateral contract,which Albrecht accepted by returning the ring; Walter is therefore bound to pay Albrecht the $500.