What hormone surge triggers ovulation in the menstrual cycle?

The hormone that triggers ovulation in the menstrual cycle is luteinizing hormone (LH). During the cycle, a rise in estrogen levels leads to a positive feedback mechanism, which results in a sudden surge of LH. This LH surge is critical because it initiates the process of ovulation, causing the mature follicle to release an egg from the ovary.

While estrogen plays a significant role in preparing the uterine lining and is involved in the regulation of the menstrual cycle, it is not responsible for triggering ovulation. Progesterone, primarily produced after ovulation, helps maintain the uterine lining for potential implantation of a fertilized egg but does not influence the ovulation process itself. Follicle-stimulating hormone (FSH) is relevant as it stimulates the growth of ovarian follicles, but again, the crucial trigger for the release of the egg is the surge in LH.

Thus, the response indicating the LH surge correctly identifies the key hormonal event leading to ovulation during the menstrual cycle.