Final answer:
Mandy is most likely using the fertility awareness method as a form of contraception by tracking her basal body temperature. Option a.
Step-by-step explanation:
Mandy is most likely using the fertility awareness method option a, as a form of contraception. The fertility awareness method involves monitoring signs of ovulation, such as tracking basal body temperature. By checking her temperature every morning, Mandy can identify the most fertile days of her menstrual cycle and avoid unprotected sexual intercourse during that time.