The correct option is B Corpus luteum
Corpus luteum is the temporary endocrine structure formed in the female mammals. It is formed in the ovary at the site of follicle or sac, that has matured and has release the egg (i.e., where ovulation has taken place). It secretes progesterone, a hormone, that causes change in uterus, that make it more suitable for implantation for the fertilized ovum and nourishment of embryo.
Thus, the correct answer is option (B).