What is one primary function of progesterone during the luteal phase?

The primary function of progesterone during the luteal phase is to prepare the uterus for implantation. Following ovulation, the corpus luteum forms and secretes progesterone, which plays a critical role in modifying the endometrium, the lining of the uterus. This hormone causes the endometrium to thicken and become more vascularized, making it more conducive for a fertilized egg to implant. If implantation occurs, progesterone levels will remain elevated to support the early stages of pregnancy.

While the other functions mentioned, such as stimulating ovulation or increasing estrogen production, are vital aspects of the menstrual cycle, they do not occur during the luteal phase, but rather in the earlier phases or general hormonal regulation. The enhancement of cervical mucus is more associated with the follicular phase and ovulation, where estrogen predominates, rather than being a primary action of progesterone. Therefore, the focus on progesterone’s role in preparing the uterus clearly identifies option B as the correct answer.