Answer: Convenience sample
Explanation:
A convenience sample is a type of non-probability sampling method where the sample is taken from a group of people which is easy to reach.
For example, a person standing at a store and asking people to answer questions would be an example of a convenience sample.
Given sample : A researcher randomly selects 5 local fast food restaurants and the ask all school age children at those restaurants their on the new town curfew.
Hence, the described sample is convenience sample.