Which of the following statement is correct?

Graafian follicle transform as the corpus luteum after the ovulation. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy. It sustains till the first trimester of pregnancy after which the function is taken over by the placenta. In the absence of fertilisation, the corpus luteum degenerates into corpus albicans.