Final answer:
Plan B is available over-the-counter for women ages 17 and older. It should be taken within 72 hours after unprotected sex and is not intended for regular use as a birth control method.
Step-by-step explanation:
Plan B, which is an emergency contraception pill, is available over-the-counter (OTC) for women ages 17 and older in the United States. This means that you must be at least 17 years old to purchase Plan B without a prescription. It is important to note that Plan B should be taken within 72 hours after unprotected sex for the best chances of effectiveness. It works by stopping the ovaries from releasing an egg or preventing the sperm from joining with the egg. However, it should not be used as a regular method of birth control.