Which One of the Following Is Enforceable

Which one of the following is enforceable?

A) Mr. Ho promised to give his needy friend Mr. Jahn $100.
B) Ms. Jones promised to pay an additional $100 to Mr. Wood if Wood finished the existing contract on time, according to the terms of the contract.
C) Mr. Baker was so sick of an old chair that, when Mr. Venson offered him $10 for it, he agreed (i.e., promised to sell it to him) , although the market value of the chair was $80.
D) Ms. Goode promised to send $10 to Mr. Paul, who kindly came and warned her when he saw a tow truck approach her car.
E) An ad in the paper promises to pay $5 for the return of a lost ring, but the person who finds and returns the ring never saw the offer in the newspaper.