When the choice belongs to the obligor, if all the items of performance contemplated in the alternative obligation have become impossible and the impossibility of one or more is due to the fault of the obligor, he is liable for the damages resulting from his failure to render the last item that became impossible.
If the impossibility of one or more items is due to the fault of the obligee, the obligor is not bound to deliver any of the items that remain.
La. C.C. § 1814