A woman of lax moral

Answer: Option B

One word substitute is Harlot.

Prostitute: a person, in particular a woman, who engages in sexual activity for payment.
Harlot: a woman who has many casual sexual encounters or relationships.
Concubine: (in polygamous societies) a woman who lives with a man but has lower status than his wife or wives.
Hostess: a woman who receives or entertains guests.