When you are pulled over for a traffic violation, you are technically being detained by law enforcement because you are not free to drive away. You should explain this in your questionnaire. It is unlikely that a minor traffic violation would result in disqualification from being hired in law enforcement. However, misrepresenting even a minor detail on your application could be disastrous for you.
Nothing in this answer constitutes an agreement to represent you in any criminal case. Additionally, the information provided above does not constitute legal advice.
Mr. Garbe is correct. You may be able to call the agency you are completing the application for to clarify what they are asking about.
The information provided does not constitute legal advice and is presented without any representation or warranty whatsoever, including as to the accuracy or completeness of the information. Always contact an attorney when seeking legal advice.