What event is defined as the rupture of a mature follicle?

The event defined as the rupture of a mature follicle is ovulation. During the menstrual cycle, a follicle develops in the ovary, containing an egg. When the follicle reaches maturity, a surge in luteinizing hormone (LH) triggers the follicle to rupture, releasing the egg into the fallopian tube. This process is crucial for reproduction, as it allows for the possibility of fertilization by sperm.

This definition contrasts with the other choices: menstruation refers to the shedding of the uterine lining when pregnancy does not occur; fertilization is the union of sperm and egg, typically occurring in the fallopian tube after ovulation; and implantation involves the attachment of the fertilized egg to the uterine lining, occurring after fertilization. Therefore, ovulation is specifically the event that marks the release of a mature egg and is critical for the reproductive process.