Final answer:
ACOG recommends that women ages 21-29 should have a Pap smear every three years.
Step-by-step explanation:
The American College of Obstetricians and Gynecologists (ACOG) recommends that women ages 21-29 should have a Pap smear every three years. This is the general guideline for routine screening in this age group, as long as there are no abnormal results or other risk factors. However, it's important to note that individual circumstances and medical history may warrant more frequent screenings, so it's always best to consult with a healthcare provider.