Imagine many years ago that I gave a woman a gift of an engagement ring, and a few weeks after accepting the ring, she broke off the engagement. Which of the following is correct under positive law?

a. Since it was a gift, the woman can keep the ring.

b. Since it was a contract to marry, the woman can keep the ring.

c. Since it was a bailment, the woman has to give it back to me.

d. Since it was a conditional gift, the woman has to give it back to me.