The correct option is A Progesterone
The corpus leuteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. The endometrium is essential for the implantation of the fertilised ovum and other events of pregnancy. In the absence of fertilisation, the corpus leuteum degenerates. This causes disintegration of the endometrium leading to menstruation. The menstrual flow results due to the breakdown of the endometrial lining of the uterus and blood vessels which form liquid that comes out through the vagina.