Final answer:
The adjective 'luteal' refers to the corpus luteum, a structure in the ovaries responsible for hormone secretion during the luteal phase of the menstrual cycle.
Step-by-step explanation:
The adjective luteal refers specifically to the corpus luteum, which is an endocrine structure in the ovaries that forms after a follicle has released its egg during ovulation.
The luteal phase of the menstrual cycle is when the corpus luteum is active, producing important hormones like progesterone that are essential for the maintenance of pregnancy should fertilization occur. This process is regulated by a pituitary hormone called luteinizing hormone (LH) that stimulates the formation of the corpus luteum from the remnants of the ovarian follicle post-ovulation. Therefore, the correct answer is b) the corpus luteum.