If, after being freed, the slave-girl does not know that she has the option (of choice), then when she comes to know, the option remains for her, even if intercourse has already taken place.
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 2425
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 1248، 1251»