The option open to the survivor lapses if he has not exercised it, by notification to the heirs of the predeceased, within one month of the day on which they have given him formal notice to take sides. Such formal notice may not be given before the expiry of the period provided for in article 792.
When made within this period, the notification constitutes a sale on the day the option is exercised or, where applicable, constitutes a partition transaction.