Final answer:
During ovulation, a woman's basal body temperature will increase.
Step-by-step explanation:
The nurse instructs the woman that during ovulation, her basal body temperature will increase. Basal body temperature is the lowest body temperature when the body is at rest and it normally rises after ovulation occurs. By tracking changes in basal body temperature, a woman can identify when ovulation has occurred, indicating a fertile period of the menstrual cycle.