Big Bank Is a Major Creditor of Bonwill Department Store

Big Bank is a major creditor of Bonwill Department Store.After a major loss in profits due to poor holiday sales,Big Bank decides to help keep Bonwill from bankruptcy.Big Bank orally promises Mary Tudor,a supplier of Bonwill's,that it will guarantee Bonwill's payment for goods that Mary sells to Bonwill.Most likely,Big Bank's oral agreement:

A) is unenforceable under the statute of frauds.
B) is unenforceable because it is a collateral contract.
C) is enforceable under the "main purpose" or "leading object" exception to the statute.
D) is enforceable because a collateral contract is not covered under the statute of frauds.