6. What sequence of events occurs in the female reproductive tract during menstruation? A. Hormones signal the lining of the uterus to thicken; this thickened lining produces bleeding known as menstrual flow.

B. Hormones signal the lining of the uterus to break down; it sloughs off and passes out of the body; later the uterine lining begins to thicken and start the process over again.

C. An egg is released from the ovary; it travels down the fallopian tube to the uterus, where it implants; if sperm are present, a pregnancy begins.

D. An egg is released from the ovary causing a bloody discharge; if sperm are present the egg may be fertilized in the uterus and implant in the fallopian tube.