Final answer:
The basal body temperature method of contraception involves tracking a woman's resting body temperature throughout her menstrual cycle. On day 12, if the temperature is still low, it is not safe to have unprotected sex.
Step-by-step explanation:
The basal body temperature method is a form of fertility awareness where a woman tracks her body temperature throughout her menstrual cycle. This method involves checking and charting the body's lowest resting temperature each morning before getting out of bed.
On day 12 of her menstrual cycle, if a woman's basal body temperature is still low, it is not safe for her to have unprotected sexual intercourse because it indicates that ovulation has not yet occurred. The basal body temperature rises after ovulation, so a low temperature suggests that she is not currently fertile.