Barbara, a Wealthy Widow, Promises the Pastor of Her Church

Barbara, a wealthy widow, promises the pastor of her church that she will donate $30,000 to the church to help pay off its mortgage if the stewardship committee can obtain enough pledges for the balance of the $60,000 mortgage. Other pledges are obtained to pay off the mortgage, but now Barbara has changed her mind and plans to take an around-the-world cruise instead. In this case:

A) Barbara's promise to pay $30,000 is enforceable because it was a promise made to satisfy a preexisting moral obligation.
B) the promise to pay $30,000 is a promise to give a gift and is therefore not enforceable.
C) under the Restatement of Contracts, Barbara's promise is enforceable.
D) Two of these.