Final answer:
The rhythm method, also known as the fertility awareness method, is true for birth control where a woman avoids unprotected sex during ovulation. Tracking methods like basal body temperature are less reliable as contraception, with a failure rate of 20 to 25 percent.
Step-by-step explanation:
The rhythm method of birth control is a behavioral contraceptive method where a woman monitors signs of ovulation and abstains from unprotected vaginal intercourse during her most fertile days to prevent pregnancy. This is known as the fertility awareness method. It is true that a woman practicing this method must avoid sex when ovulating, as this is the time when she is most likely to get pregnant.
If today is day 12 of her menstrual cycle and a woman's basal body temperature is still low, it may not be safe to have unprotected sexual intercourse since ovulation could occur soon, potentially leading to pregnancy. These methods, including tracking basal body temperature and cervical mucus, have a typical-use failure rate of at least 20 to 25 percent, meaning it's not as reliable as other forms of contraception like hormonal methods or IUDs.