Age Range is a determining factor in screening respondents. Rather than ask a respondent their exact age, which many people are hesitant to reveal to a stranger on the phone, you ask them to stop you when you read the age range which contains their age.
When you select the respondent's age range from the drop box, the computer will either accept this age range as valid, or give you a Wrong Age message in the interviewer Script box. A valid entry advances you to the next option, Gender, while an invalid age range forces you to either:
A) speak with someone else in the household who might qualify,
B) make this respondent Not Qualified if there is nobody else available.
A third option might be to Set a Callback if there is someone who might qualify in the household, but is not available to participate in the survey at this time.