P.R. Laws tit. 31, § 3086
When an option has been expressly granted the creditor the obligation shall cease to be alternative from the day on which notice of said option may have been given to the debtor.
Until then the liability of the debtor shall be governed by the following rules:
(1) If any of the things should have been lost by a fortuitous event, he shall perform by delivering the one which the creditor may select from among those remaining, or the one remaining if only one should exist.
(2) If the loss of any of the things should have been caused by the fault of the debtor the creditor may claim any of those remaining or the value of the one which has disappeared by the fault of the debtor.
(3) If all the things should have been lost by the fault of the debtor the creditor shall have a right to select the value of any one of them.
The same rules shall be applied to the obligations of doing or not doing, in case that any or all of the prestations should be impossible.
History —Civil Code, 1930, § 1089.