With Regard Only to the Requirement of Consideration, Which One

Multiple Choice

With regard only to the requirement of consideration, which one of the following would be a binding contract?

A) A promise by Tom to drive a co-worker to Timmins, Ontario
B) A promise to give $10 in exchange for a promise to give a can of pop
C) A promise by Mr. Brent to pay $25 to John, who found and returned Brent's wallet, which Brent didn't even know he had lost until John delivered it
D) An agreement between a contractor and a homeowner that the owner would pay an additional $1000 if the contractor would complete the existing contract according to all its terms
E) A written promise, but not under seal, to give John $50 on Saturday