Final answer:
The rhythm method, a fertility awareness method of contraception, requires couples to abstain from unprotected intercourse during the 5 days before and after ovulation to avoid pregnancy.
Step-by-step explanation:
Regarding natural methods of contraception, the rhythm method is a type of fertility awareness method where the most fertile days of a woman’s menstrual cycle are estimated, and unprotected vaginal intercourse is avoided during this time. To effectively apply the rhythm method, a couple should abstain from intercourse during the 5 days before and after ovulation, making choice d the correct answer. Ovulation is the release of an egg from the ovaries and it typically occurs in the middle of the menstrual cycle. Since sperm can live inside a woman's body for approximately five days and the egg can be fertilized for up to 24 hours after being released, this window is considered the most fertile and hence the most critical to avoid unprotected intercourse if using the rhythm method as contraception.