Which process describes the shedding of the uterine lining?

The process that describes the shedding of the uterine lining is known as menstruation. During this menstrual cycle, if a fertilized egg does not implant in the uterine lining, the levels of hormones such as estrogen and progesterone decline, leading to the breakdown and shedding of the endometrial tissue. This shedding is what constitutes the menstrual flow.

In the context of the other options, ovulation refers to the release of an egg from the ovary, which occurs mid-cycle but does not involve the shedding of the uterine lining. The follicular phase is the first part of the menstrual cycle, leading up to ovulation, during which the uterine lining is actually building up in preparation for a potential pregnancy. The estrous cycle is a reproductive cycle occurring in some mammals, distinct from the menstrual cycle, and does not involve the shedding of the uterine lining in a similar fashion. Thus, menstruation is the correct term associated with the shedding of the uterine lining.