Final answer:
The rhythm method, also known as the fertility awareness method, is a birth control approach where sexual activity is avoided during the most fertile times of the menstrual cycle.
Step-by-step explanation:
The birth control method in which sexual intercourse is avoided during those days of the menstrual cycle in which fertilization is most likely to occur is known as the rhythm method or fertility awareness method. This method requires a woman to monitor signs of ovulation and avoid unprotected vaginal intercourse during her most fertile days. This often involves tracking basal body temperature or changes in cervical mucus. The other options listed, such as the diaphragm, emergency contraception, and intrauterine device (IUD), work differently. The diaphragm is a barrier method that physically blocks sperm from entering the uterus. Emergency contraception is used after unprotected sex to prevent pregnancy, and an IUD is a device inserted into the uterus to prevent fertilization or implantation.