Final answer:
The pill is a contraceptive method that is 99% effective when used properly, but only 91% effective in real life.
Step-by-step explanation:
The contraceptive that is 99% effective when used properly but only 91% effective in real life is the pill. The pill is a hormonal contraceptive method that contains synthetic hormones which prevent ovulation, thicken the cervical mucus, and change the lining of the uterus to make it less suitable for implantation of a fertilized egg. It is important to note that the effectiveness of the pill can vary depending on proper and consistent use.
Learn more about Contraception