Mark, a College Student, Agreed to Sell His Horse to Henry

Mark, a college student, agreed to sell his horse to Henry for $1,000. The contract required Mark to take the horse on that same day to Idlewild Stables where Henry was going to board the horse. Henry paid Mark the money, patted the horse and said, "I'm glad you're mine, you beauty," and drove off. Mark then led the horse into the trailer and set off for the two-hour drive to Idlewild. Has there been a sale?

A) No, not until delivery to Idlewild.
B) No, not until Henry sees the horse again.
C) Yes, since Henry already paid for it.
D) Yes, since the contract was made earlier in the day.